Faculty
Assistant professor
Room 139
+81 (0)75 753 3744
kitagHelloUglyBot!awa.shuHelloUglyBot!nsaku.8HelloUglyBot!u@kyoto-u.ac.jp
my publications in the group follow:
2023
68.
H Fujibayashi, K Kinjo, G Nakamine, S Kitagawa, K Ishida, Y Tokunaga, H Sakai, S Kambe, A Nakamura, Y Shimizu, Y Homma, D Li, F Honda, D Aoki
Low-Temperature Magnetic Fluctuations Investigated by 125Te-NMR on the Uranium-Based Superconductor UTe2 Journal Article
In: Journal of the Physical Society of Japan, vol. 92, pp. 053702, 2023.
@article{H.Fujibayashi_JPSJ_2023,
title = {Low-Temperature Magnetic Fluctuations Investigated by 125Te-NMR on the Uranium-Based Superconductor UTe2},
author = {H Fujibayashi and K Kinjo and G Nakamine and S Kitagawa and K Ishida and Y Tokunaga and H Sakai and S Kambe and A Nakamura and Y Shimizu and Y Homma and D Li and F Honda and D Aoki},
doi = {10.7566/JPSJ.92.053702},
year = {2023},
date = {2023-04-26},
urldate = {2023-04-26},
journal = {Journal of the Physical Society of Japan},
volume = {92},
pages = {053702},
abstract = {To investigate the static and dynamic magnetic properties on the uranium-based superconductor UTe2, we measured the NMR Knight shift K and the nuclear spin–lattice relaxation rate 1/T1 in H || a by 125Te-NMR on a 125Te-enriched single-crystal sample. 1/T1T in H || a is much smaller than 1/T1T in H || b and c, and magnetic fluctuations along each axis are derived from the 1/T1T measured in H parallel to all three crystalline axes. The magnetic fluctuations are almost identical at two Te sites and isotropic at high temperatures, but become anisotropic below 40 K, where heavy-fermion state is formed. The character of magnetic fluctuations in UTe2 is discussed with the comparison to its static susceptibility and the results on other U-based superconductors. It is considered that the magnetic fluctuations probed with the NMR measurements are determined by the magnetic properties inside the two-leg ladder formed by U atoms, which are dominated by the qa = 0 ferromagnetic fluctuations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
To investigate the static and dynamic magnetic properties on the uranium-based superconductor UTe2, we measured the NMR Knight shift K and the nuclear spin–lattice relaxation rate 1/T1 in H || a by 125Te-NMR on a 125Te-enriched single-crystal sample. 1/T1T in H || a is much smaller than 1/T1T in H || b and c, and magnetic fluctuations along each axis are derived from the 1/T1T measured in H parallel to all three crystalline axes. The magnetic fluctuations are almost identical at two Te sites and isotropic at high temperatures, but become anisotropic below 40 K, where heavy-fermion state is formed. The character of magnetic fluctuations in UTe2 is discussed with the comparison to its static susceptibility and the results on other U-based superconductors. It is considered that the magnetic fluctuations probed with the NMR measurements are determined by the magnetic properties inside the two-leg ladder formed by U atoms, which are dominated by the qa = 0 ferromagnetic fluctuations.
67.
S Ogata, S Kitagawa, K Kinjo, K Ishida, M Brando, E Hassinger, C Geibel, S Khim
Parity transition of spin-singlet superconductivity using sub-lattice degrees of freedom Journal Article
In: Physical Review Letters, vol. 130, pp. 166001 , 2023.
@article{S.Ogata_PRL_2023,
title = {Parity transition of spin-singlet superconductivity using sub-lattice degrees of freedom},
author = {S Ogata and S Kitagawa and K Kinjo and K Ishida and M Brando and E Hassinger and C Geibel and S Khim},
url = {https://arxiv.org/abs/2304.10032},
doi = {10.1103/PhysRevLett.130.166001},
year = {2023},
date = {2023-04-19},
urldate = {2023-04-19},
journal = {Physical Review Letters},
volume = {130},
pages = {166001 },
abstract = {Recently, a superconducting (SC) transition from low-field (LF) to high-field (HF) SC states was reported in CeRh2As2, indicating the existence of multiple SC states. It has been theoretically noted that the existence of two Ce sites in the unit cell, the so-called sub-lattice degrees of freedom owing to the local inversion symmetry breaking at the Ce sites, can lead to the appearance of multiple SC phases even under an interaction inducing spin-singlet superconductivity. CeRh2As2 is considered as the first example of multiple SC phases owing to this sub-lattice degree of freedom. However, microscopic information about the SC states has not yet been reported. In this study, we measured the SC spin susceptibility at two crystallographically inequivalent As sites using nuclear magnetic resonance for various magnetic fields. Our experimental results strongly indicate a spin-singlet state in both SC phases. In addition, the antiferromagnetic phase, which appears within the SC phase, only coexists with the LF SC phase; there is no sign of magnetic ordering in the HF SC phase. The present work reveals unique SC properties originating from the locally noncentrosymmetric characteristics. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recently, a superconducting (SC) transition from low-field (LF) to high-field (HF) SC states was reported in CeRh2As2, indicating the existence of multiple SC states. It has been theoretically noted that the existence of two Ce sites in the unit cell, the so-called sub-lattice degrees of freedom owing to the local inversion symmetry breaking at the Ce sites, can lead to the appearance of multiple SC phases even under an interaction inducing spin-singlet superconductivity. CeRh2As2 is considered as the first example of multiple SC phases owing to this sub-lattice degree of freedom. However, microscopic information about the SC states has not yet been reported. In this study, we measured the SC spin susceptibility at two crystallographically inequivalent As sites using nuclear magnetic resonance for various magnetic fields. Our experimental results strongly indicate a spin-singlet state in both SC phases. In addition, the antiferromagnetic phase, which appears within the SC phase, only coexists with the LF SC phase; there is no sign of magnetic ordering in the HF SC phase. The present work reveals unique SC properties originating from the locally noncentrosymmetric characteristics.
66.
K Kinjo, H Fujibayashi, S Kitagawa, K Ishida, Y Tokunaga, H Sakai, S Kambe, A Nakamura, Y Shimizu, Y Homma, D. X Li, F Honda, D Aoki, K Hiraki, M Kimata, T Sasaki
Change of superconducting character in UTe2 induced by magnetic field Journal Article
In: Physical Review B, vol. 107, iss. 06, pp. L060502, 2023.
@article{K.Kinjo_PRB_2023,
title = {Change of superconducting character in UTe2 induced by magnetic field},
author = {K Kinjo and H Fujibayashi and S Kitagawa and K Ishida and Y Tokunaga and H Sakai and S Kambe and A Nakamura and Y Shimizu and Y Homma and D. X Li and F Honda and D Aoki and K Hiraki and M Kimata and T Sasaki},
url = {https://arxiv.org/abs/2206.02444},
doi = {10.1103/PhysRevB.107.L060502},
year = {2023},
date = {2023-02-10},
urldate = {2023-02-10},
journal = {Physical Review B},
volume = {107},
issue = {06},
pages = {L060502},
abstract = {UTe2 is a recently discovered spin-triplet superconductor. One of the characteristic features of UTe2 is a magnetic field (H)-boosted superconductivity >16 T when H is applied exactly parallel to the b axis. To date, this superconducting (SC) state has not been thoroughly investigated, and the SC properties as well as the spin state of this high-H SC (HHSC) phase are not well understood. In this letter, we performed AC magnetic susceptibility and nuclear magnetic resonance measurements and found that, up to 24.8 T, the HHSC state has bulk nature and is quite sensitive to the H angle and that its SC character is different from that in the low-H SC (LHSC) state. The dominant spin component of the spin-triplet pair is along the a axis in the LHSC state but is changed in the HHSC state along the b axis. Our results indicate that H -induced multiple SC states originate from the remaining spin degrees of freedom.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
UTe2 is a recently discovered spin-triplet superconductor. One of the characteristic features of UTe2 is a magnetic field (H)-boosted superconductivity >16 T when H is applied exactly parallel to the b axis. To date, this superconducting (SC) state has not been thoroughly investigated, and the SC properties as well as the spin state of this high-H SC (HHSC) phase are not well understood. In this letter, we performed AC magnetic susceptibility and nuclear magnetic resonance measurements and found that, up to 24.8 T, the HHSC state has bulk nature and is quite sensitive to the H angle and that its SC character is different from that in the low-H SC (LHSC) state. The dominant spin component of the spin-triplet pair is along the a axis in the LHSC state but is changed in the HHSC state along the b axis. Our results indicate that H -induced multiple SC states originate from the remaining spin degrees of freedom.
2022
65.
C-Wen Chuang, S Souma, A Moriya, K Nakayama, A Ikeda, M Kawaguchi, K Obata, S Ranjan Saha, H Takahashi, S Kitagawa, K Ishida, K Tanaka, M Kitamura, K Horiba, H Kumigashira, T Takahashi, S Yonezawa, J Paglione, Y Maeno, T Sato
Fermiology of a topological line-nodal compound CaSb2 and its implication to superconductivity: Angle-resolved photoemission study Journal Article
In: Physical Review Materials, vol. 6, iss. 10, pp. 104203, 2022.
@article{CaSb2ARPES,
title = {Fermiology of a topological line-nodal compound CaSb2 and its implication to superconductivity: Angle-resolved photoemission study},
author = {C-Wen Chuang and S Souma and A Moriya and K Nakayama and A Ikeda and M Kawaguchi and K Obata and S Ranjan Saha and H Takahashi and S Kitagawa and K Ishida and K Tanaka and M Kitamura and K Horiba and H Kumigashira and T Takahashi and S Yonezawa and J Paglione and Y Maeno and T Sato},
url = {https://arxiv.org/abs/2211.15083},
doi = {10.1103/PhysRevMaterials.6.104203},
year = {2022},
date = {2022-10-24},
urldate = {2022-10-24},
journal = {Physical Review Materials},
volume = {6},
issue = {10},
pages = {104203},
abstract = {We performed angle-resolved photoemission spectroscopy with microfocused beam on a topological line-nodal compound CaSb2 which undergoes a superconducting transition at the onset Tc ∼ 1.8 K, to clarify the Fermi-surface topology relevant to the occurrence of superconductivity. We found that a three-dimensional hole pocket at the Γ point is commonly seen for two types of single-crystalline samples fabricated by different growth conditions. On the other hand, the carrier-doping level estimated from the position of the chemical potential was found to be sensitive to the sample fabrication condition. The cylindrical electron pocket at the Y(C) point predicted by the calculations is absent in one of the two samples, despite the fact that both samples commonly show superconductivity with similar Tc's. This suggests a key role of the three-dimensional hole pocket to the occurrence of superconductivity, and further points to an intriguing possibility to control the topological nature of superconductivity by carrier tuning in CaSb2.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We performed angle-resolved photoemission spectroscopy with microfocused beam on a topological line-nodal compound CaSb2 which undergoes a superconducting transition at the onset Tc ∼ 1.8 K, to clarify the Fermi-surface topology relevant to the occurrence of superconductivity. We found that a three-dimensional hole pocket at the Γ point is commonly seen for two types of single-crystalline samples fabricated by different growth conditions. On the other hand, the carrier-doping level estimated from the position of the chemical potential was found to be sensitive to the sample fabrication condition. The cylindrical electron pocket at the Y(C) point predicted by the calculations is absent in one of the two samples, despite the fact that both samples commonly show superconductivity with similar Tc's. This suggests a key role of the three-dimensional hole pocket to the occurrence of superconductivity, and further points to an intriguing possibility to control the topological nature of superconductivity by carrier tuning in CaSb2.
64.
M Manago, G Motoyama, S Nishigori, K Fujiwara, K Kinjo, S Kitagawa, K Ishida, K Akiba, S Araki, T C Kobayashi, Hisatomo Harima
Site Split of Antiferromagnetic α-Mn Revealed by 55Mn Nuclear Magnetic Resonance Journal Article
In: Journal of the Physical Society of Japan, vol. 91, iss. 11, pp. 113701, 2022.
@article{M.Manago_JPSJ_2022,
title = {Site Split of Antiferromagnetic α-Mn Revealed by 55Mn Nuclear Magnetic Resonance},
author = {M Manago and G Motoyama and S Nishigori and K Fujiwara and K Kinjo and S Kitagawa and K Ishida and K Akiba and S Araki and T C Kobayashi and Hisatomo Harima},
url = {https://arxiv.org/abs/2210.02754},
doi = {10.7566/JPSJ.91.113701},
year = {2022},
date = {2022-10-06},
urldate = {2022-10-06},
journal = {Journal of the Physical Society of Japan},
volume = {91},
issue = {11},
pages = {113701},
abstract = {The magnetic structure of antiferromagnetic α-Mn has been unclarified for almost 70 years since its magnetism was discovered. We measured the zero-field nuclear magnetic resonance spectra of antiferromagnetic α-Mn to obtain further insight into magnetism below TN = 95 K. The site II spectra split into two sites with five subpeaks owing to quadrupole interaction, and this shows that the ordered moments at site II are slightly tilted from the [001] direction. The site III spectra revealed that this site splits into four sites below TN. These findings clearly demonstrate that the antiferromagnetic α-Mn symmetry is lower than previously considered.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The magnetic structure of antiferromagnetic α-Mn has been unclarified for almost 70 years since its magnetism was discovered. We measured the zero-field nuclear magnetic resonance spectra of antiferromagnetic α-Mn to obtain further insight into magnetism below TN = 95 K. The site II spectra split into two sites with five subpeaks owing to quadrupole interaction, and this shows that the ordered moments at site II are slightly tilted from the [001] direction. The site III spectra revealed that this site splits into four sites below TN. These findings clearly demonstrate that the antiferromagnetic α-Mn symmetry is lower than previously considered.
63.
S Kitagawa, T Kobayashi, F Hori, K Ishida, A H Nevidomskyy, L Qian, E Morosan
Enhancement of charge-neutral fermionic excitations near the spin-flop transition in the magnetic Kondo material YbIr3Si7 Journal Article
In: Physical Review B, vol. 106, pp. L100405, 2022.
@article{S.Kitagawa_PRB_2022,
title = {Enhancement of charge-neutral fermionic excitations near the spin-flop transition in the magnetic Kondo material YbIr3Si7},
author = {S Kitagawa and T Kobayashi and F Hori and K Ishida and A H Nevidomskyy and L Qian and E Morosan},
url = {https://doi.org/10.1103/PhysRevB.106.L100405
https://arxiv.org/abs/2209.10844},
doi = {10.1103/PhysRevB.106.L100405},
year = {2022},
date = {2022-09-16},
urldate = {2022-09-16},
journal = {Physical Review B},
volume = {106},
pages = {L100405},
abstract = {The new Kondo material YbIr3Si7, similar to other Kondo insulators, has been reported to exhibit charge-neutral fermionic excitations through measurements of specific heat and thermal conductivity at low temperatures.
We performed 29Si−NMR on YbIr3Si7 to investigate the magnetic response of charge-neutral fermions from a microscopic perspective. In low magnetic fields parallel to the c axis, a single NMR peak in the paramagnetic state splits into three peaks below TN.
In contrast, only a slight shift of the single NMR peak was observed in high magnetic fields. This spectral change as a function of the c
-axis magnetic field is interpreted as a spin-flop transition, at which the magnetic moments oriented along the c axis antiferromagnetic (AFM-I) phase are rotated to the ab plane with a ferromagnetic component along the c-axis (AFM-II phase). In the vicinity of the spin-flop magnetic field
HM, the nuclear spin-lattice relaxation rate 1/T1 was found to be proportional to temperature at low temperatures, indicating the existence of charge-neutral fermions. Furthermore, a peak of 1/T1 versus the c-axis magnetic field suggests that the charge-neutral fermions in YbIr3Si7 are closely related to its magnetic properties. Our findings shed light on the origin of charge-neutral fermions in insulators.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The new Kondo material YbIr3Si7, similar to other Kondo insulators, has been reported to exhibit charge-neutral fermionic excitations through measurements of specific heat and thermal conductivity at low temperatures.
We performed 29Si−NMR on YbIr3Si7 to investigate the magnetic response of charge-neutral fermions from a microscopic perspective. In low magnetic fields parallel to the c axis, a single NMR peak in the paramagnetic state splits into three peaks below TN.
In contrast, only a slight shift of the single NMR peak was observed in high magnetic fields. This spectral change as a function of the c
-axis magnetic field is interpreted as a spin-flop transition, at which the magnetic moments oriented along the c axis antiferromagnetic (AFM-I) phase are rotated to the ab plane with a ferromagnetic component along the c-axis (AFM-II phase). In the vicinity of the spin-flop magnetic field
HM, the nuclear spin-lattice relaxation rate 1/T1 was found to be proportional to temperature at low temperatures, indicating the existence of charge-neutral fermions. Furthermore, a peak of 1/T1 versus the c-axis magnetic field suggests that the charge-neutral fermions in YbIr3Si7 are closely related to its magnetic properties. Our findings shed light on the origin of charge-neutral fermions in insulators.
We performed 29Si−NMR on YbIr3Si7 to investigate the magnetic response of charge-neutral fermions from a microscopic perspective. In low magnetic fields parallel to the c axis, a single NMR peak in the paramagnetic state splits into three peaks below TN.
In contrast, only a slight shift of the single NMR peak was observed in high magnetic fields. This spectral change as a function of the c
-axis magnetic field is interpreted as a spin-flop transition, at which the magnetic moments oriented along the c axis antiferromagnetic (AFM-I) phase are rotated to the ab plane with a ferromagnetic component along the c-axis (AFM-II phase). In the vicinity of the spin-flop magnetic field
HM, the nuclear spin-lattice relaxation rate 1/T1 was found to be proportional to temperature at low temperatures, indicating the existence of charge-neutral fermions. Furthermore, a peak of 1/T1 versus the c-axis magnetic field suggests that the charge-neutral fermions in YbIr3Si7 are closely related to its magnetic properties. Our findings shed light on the origin of charge-neutral fermions in insulators.
62.
T Taniguchi, S Kitagawa, K Ishida, S Asano, K Kudo, M Takahama, P Xie, T Noji, M Fujita
139La-NMR Study of Spin Dynamics Coupled with Hole Mobility in T*-type La0.86Eu0.86Sr0.28CuO4−δ Journal Article
In: Journal of the Physical Society of Japan, vol. 91, iss. 07, pp. 074710, 2022.
@article{T.Taniguchi_JPSJ_2022,
title = {139La-NMR Study of Spin Dynamics Coupled with Hole Mobility in T*-type La0.86Eu0.86Sr0.28CuO4−δ},
author = {T Taniguchi and S Kitagawa and K Ishida and S Asano and K Kudo and M Takahama and P Xie and T Noji and M Fujita},
url = {https://arxiv.org/abs/2110.12333},
doi = {10.7566/JPSJ.91.074710},
year = {2022},
date = {2022-06-22},
urldate = {2022-06-22},
journal = {Journal of the Physical Society of Japan},
volume = {91},
issue = {07},
pages = {074710},
abstract = {In T*-type cuprate oxides with five-oxygen coordination, the relationship between spin correlations and doped carriers has not been well understood. To clarify this relationship, and the magnetic and superconducting (SC) properties of T*-type cuprate oxides, we performed 139La-nuclear magnetic resonance (NMR) and electrical resistivity measurements on as-sintered (AS) and oxidation-annealed (OA) polycrystalline T*-type La0.86Eu0.86S0.28CuO4 (LESCO) to investigate its magnetic and SC properties. Upon cooling, the NMR spectrum of AS LESCO broadened below 3 K, where the nuclear spin–lattice relaxation rate 1/T1 with respect to the temperature exhibited a maximum, indicating the appearance of static magnetism. The temperature dependence of 1/T1 between 3 and 20 K was similar to that of resistivity, which displays semiconducting behavior. Furthermore, it was found that the energy scales of the transport gap and spin dynamics were comparable. These results suggest a close connection between the mobility of the doped carriers and low-energy spin dynamics, as reported for lightly doped T-type La2−xSrxCuO4. In the OA SC sample, we confirmed the absence of a magnetic order and the linear relation between 1/T1 and T above 10 K. These results suggest that the magnetic state coupled with holes markedly changes to the weakly correlated metallic state by oxidation annealing in the T*-type LESCO with x = 0.28.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In T*-type cuprate oxides with five-oxygen coordination, the relationship between spin correlations and doped carriers has not been well understood. To clarify this relationship, and the magnetic and superconducting (SC) properties of T*-type cuprate oxides, we performed 139La-nuclear magnetic resonance (NMR) and electrical resistivity measurements on as-sintered (AS) and oxidation-annealed (OA) polycrystalline T*-type La0.86Eu0.86S0.28CuO4 (LESCO) to investigate its magnetic and SC properties. Upon cooling, the NMR spectrum of AS LESCO broadened below 3 K, where the nuclear spin–lattice relaxation rate 1/T1 with respect to the temperature exhibited a maximum, indicating the appearance of static magnetism. The temperature dependence of 1/T1 between 3 and 20 K was similar to that of resistivity, which displays semiconducting behavior. Furthermore, it was found that the energy scales of the transport gap and spin dynamics were comparable. These results suggest a close connection between the mobility of the doped carriers and low-energy spin dynamics, as reported for lightly doped T-type La2−xSrxCuO4. In the OA SC sample, we confirmed the absence of a magnetic order and the linear relation between 1/T1 and T above 10 K. These results suggest that the magnetic state coupled with holes markedly changes to the weakly correlated metallic state by oxidation annealing in the T*-type LESCO with x = 0.28.
61.
K Kinjo, M Manago, S Kitagawa, Z Q Mao, S Yonezawa, Y Maeno, K. Ishida
Superconducting spin smecticity evidencing the Fulde-Ferrell-Larkin-Ovchinnikov state in Sr2RuO4 Journal Article
In: Science, vol. 376, iss. 6591, pp. 397-400, 2022.
@article{K.Kinjo_Science_2022,
title = {Superconducting spin smecticity evidencing the Fulde-Ferrell-Larkin-Ovchinnikov state in Sr2RuO4},
author = {K Kinjo and M Manago and S Kitagawa and Z Q Mao and S Yonezawa and Y Maeno and K. Ishida},
url = {https://www.science.org/doi/10.1126/science.abb0332},
doi = {10.1126/science.abb0332},
year = {2022},
date = {2022-04-21},
journal = {Science},
volume = {376},
issue = {6591},
pages = {397-400},
abstract = {Translational symmetry breaking is antagonistic to static fluidity but can be realized in superconductors, which host a quantum-mechanical coherent fluid formed by electron pairs. A peculiar example of such a state is the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, induced by a time-reversal symmetry–breaking magnetic field applied to spin-singlet superconductors. This state is intrinsically accompanied by the superconducting spin smecticity, spin density–modulated fluidity with spontaneous translational-symmetry breaking. Detection of such spin smecticity provides unambiguous evidence for the FFLO state, but its observation has been challenging. Here, we report the characteristic “double-horn” nuclear magnetic resonance spectrum in the layered superconductor Sr2RuO4 near its upper critical field, indicating the spatial sinusoidal modulation of spin density that is consistent with superconducting spin smecticity. Our work reveals that Sr2RuO4 provides a versatile platform for studying FFLO physics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Translational symmetry breaking is antagonistic to static fluidity but can be realized in superconductors, which host a quantum-mechanical coherent fluid formed by electron pairs. A peculiar example of such a state is the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, induced by a time-reversal symmetry–breaking magnetic field applied to spin-singlet superconductors. This state is intrinsically accompanied by the superconducting spin smecticity, spin density–modulated fluidity with spontaneous translational-symmetry breaking. Detection of such spin smecticity provides unambiguous evidence for the FFLO state, but its observation has been challenging. Here, we report the characteristic “double-horn” nuclear magnetic resonance spectrum in the layered superconductor Sr2RuO4 near its upper critical field, indicating the spatial sinusoidal modulation of spin density that is consistent with superconducting spin smecticity. Our work reveals that Sr2RuO4 provides a versatile platform for studying FFLO physics.
60.
K Kinjo, H Fujibayashi, G Nakamine, S Kitagawa, K Ishida, Y Tokunaga, H Sakai, S Kambe, A Nakamura, Y Shimizu, Y Homma, D Li, F Honda, D Aoki
Drastic change in magnetic anisotropy of UTe2 under pressure revealed by 125Te -NMR Journal Article
In: Physical Review B, vol. 105, iss. 14, pp. L140502, 2022.
@article{K.Kinjo_PRB_2022,
title = {Drastic change in magnetic anisotropy of UTe2 under pressure revealed by 125Te -NMR},
author = {K Kinjo and H Fujibayashi and G Nakamine and S Kitagawa and K Ishida and Y Tokunaga and H Sakai and S Kambe and A Nakamura and Y Shimizu and Y Homma and D Li and F Honda and D Aoki},
url = {https://arxiv.org/abs/2203.12934},
doi = {10.1103/PhysRevB.105.L140502},
year = {2022},
date = {2022-04-06},
urldate = {2022-04-06},
journal = {Physical Review B},
volume = {105},
issue = {14},
pages = {L140502},
abstract = {To investigate the normal-state magnetic properties of UTe2 under pressure, we perform 125Te nuclear magnetic resonance (NMR) measurements up to 2 GPa. Below 1.2 GPa, the b-axis NMR Knight shift shows a broad maximum at the so-called T_chimax on cooling, which is consistent with the magnetization measurement under pressure. T_chimax decreases with increasing pressure and disappears at the critical pressure Pc = 1.7 GPa, above which superconductivity is destroyed. This tendency is also observed in the temperature dependence of the nuclear spin-lattice relaxation rate 1/T1. At low pressures, 1/T1 shows a conventional Fermi-liquid behavior (1/T1T = constant) at low temperatures, indicating the formation of the heavy-fermion state. Above Pc, 1/T1T follows a 1/T behavior without any crossover to the heavy-fermion state down to the lowest temperature (~3 K). In addition, the NMR signals disappear below 3 K, due to the influence of the magnetically ordered moments. From the pressure dependence of the T_chimax and Knight shift, it was found that the Fermi surface character is abruptly changed at Pc, and that superconductivity is observed only in the heavy-fermion state.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
To investigate the normal-state magnetic properties of UTe2 under pressure, we perform 125Te nuclear magnetic resonance (NMR) measurements up to 2 GPa. Below 1.2 GPa, the b-axis NMR Knight shift shows a broad maximum at the so-called T_chimax on cooling, which is consistent with the magnetization measurement under pressure. T_chimax decreases with increasing pressure and disappears at the critical pressure Pc = 1.7 GPa, above which superconductivity is destroyed. This tendency is also observed in the temperature dependence of the nuclear spin-lattice relaxation rate 1/T1. At low pressures, 1/T1 shows a conventional Fermi-liquid behavior (1/T1T = constant) at low temperatures, indicating the formation of the heavy-fermion state. Above Pc, 1/T1T follows a 1/T behavior without any crossover to the heavy-fermion state down to the lowest temperature (~3 K). In addition, the NMR signals disappear below 3 K, due to the influence of the magnetically ordered moments. From the pressure dependence of the T_chimax and Knight shift, it was found that the Fermi surface character is abruptly changed at Pc, and that superconductivity is observed only in the heavy-fermion state.
59.
H Fujibayashi, G Nakamine, K Kinjo, S Kitagawa, K Ishida, Y Tokunaga, H Sakai, S Kambe, A Nakamura, Y Shimizu, Y Homma, D Li, F Honda, D Aoki
Superconducting Order Parameter in UTe2 Determined by Knight Shift Measurement Journal Article
In: Journal of the Physical Society of Japan, vol. 91, no. 04, pp. 043705, 2022.
@article{H.Fujibayashi_JPSJ_2022,
title = {Superconducting Order Parameter in UTe2 Determined by Knight Shift Measurement},
author = {H Fujibayashi and G Nakamine and K Kinjo and S Kitagawa and K Ishida and Y Tokunaga and H Sakai and S Kambe and A Nakamura and Y Shimizu and Y Homma and D Li and F Honda and D Aoki},
url = {https://doi.org/10.7566/JPSJ.91.043705
https://arxiv.org/abs/2203.08598},
doi = {10.7566/JPSJ.91.043705},
year = {2022},
date = {2022-03-11},
urldate = {2022-03-11},
journal = {Journal of the Physical Society of Japan},
volume = {91},
number = {04},
pages = {043705},
abstract = {This study investigates the spin susceptibility in U-based superconductor UTe2 in the superconducting (SC) state by using Knight shift measurements for a magnetic field H along the a axis, which is the magnetic easy axis of UTe2.
Although a tiny anomaly ascribed to the SC diamagnetic effect was observed just below the SC transition temperature Tc, the a-axis Knight shift in the SC state shows no significant decrease, following the extrapolation from the normal-state temperature dependence.
This indicates that the spin susceptibility is nearly unchanged below Tc.
Considering the previous Knight shift results for H∥b and H∥c, the dominant SC state is determined to be B3u in the spin-triplet pairing, which is consistent with the spin anisotropy in the normal state.
The present result shows that UTe2 is a spin-triplet superconductor with spin degrees of freedom.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study investigates the spin susceptibility in U-based superconductor UTe2 in the superconducting (SC) state by using Knight shift measurements for a magnetic field H along the a axis, which is the magnetic easy axis of UTe2.
Although a tiny anomaly ascribed to the SC diamagnetic effect was observed just below the SC transition temperature Tc, the a-axis Knight shift in the SC state shows no significant decrease, following the extrapolation from the normal-state temperature dependence.
This indicates that the spin susceptibility is nearly unchanged below Tc.
Considering the previous Knight shift results for H∥b and H∥c, the dominant SC state is determined to be B3u in the spin-triplet pairing, which is consistent with the spin anisotropy in the normal state.
The present result shows that UTe2 is a spin-triplet superconductor with spin degrees of freedom.
Although a tiny anomaly ascribed to the SC diamagnetic effect was observed just below the SC transition temperature Tc, the a-axis Knight shift in the SC state shows no significant decrease, following the extrapolation from the normal-state temperature dependence.
This indicates that the spin susceptibility is nearly unchanged below Tc.
Considering the previous Knight shift results for H∥b and H∥c, the dominant SC state is determined to be B3u in the spin-triplet pairing, which is consistent with the spin anisotropy in the normal state.
The present result shows that UTe2 is a spin-triplet superconductor with spin degrees of freedom.
