New publications Archives - Quantum Materials Lab

Superconducting spin smecticity evidencing the Fulde-Ferrell-Larkin-Ovchinnikov state in Sr2RuO4

2022/05/232022/05/23

Translational symmetry breaking in fluid is antagonistic but can be realized insuperconductivity, which is quantum-mechanical coherent fluid formed byelectron pairs. This novel superconducting state, known as the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, can be induced by time-reversal-symmetrybreaking magnetic field applied to spin-singlet superconductors. This stateintrinsically causes the superconducting spin smecticity, spin-density-modulatedfluidity with spontaneous translational-symmetry breaking. Detection of […]

Drastic change in magnetic anisotropy of UTe2 under pressure revealed by 125Te-NMR

2022/05/232022/05/23

To investigate the normal-state magnetic properties of UTe 2 under pressure, weperform 125 Te 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 χ max on cooling, which is consistent with the magnetizationmeasurement under pressure. T χ max decreases […]

Novel law of nonlinear optical response in strongly correlated electron systems

2022/03/232022/03/29

In the Mott insulator Ca2RuO4, which is a strongly correlated material material, we observed for the first time the generation of high-order harmonics that convert a strong infrared laser beam into visible light. Our experiments show that the intensity of the generated signal follows a surprisingly simple rule. In recent years, with the development of ultrashort […]

Observation of Antiferromagnetic Order as Odd-Parity Multipoles inside the Superconducting Phase in CeRh2As2

2022/02/032022/03/08

Spatial inversion symmetry in crystal structures is closely related to the superconducting (SC) and magnetic properties of materials. Recently, several theoretical proposals that predict various interesting phenomena caused by the breaking of the local inversion symmetry have been presented. However, experimental validation has not yet progressed owing to the lack of model materials. Here we […]

Pairing interaction in superconducting UCoGe tunable by magnetic field

2021/10/182021/11/01

The mechanism of unconventional superconductivity, such as high-temperature-cuprate, Fe-based, and heavy-fermion superconductors, has been studied as a central issue in condensed-matter physics. Spin fluctuations, instead of phonons, are considered to be responsible for the formation of Cooper pairs, and many efforts have been made to confirm this mechanism experimentally. Although a qualitative consensus seems to […]

Peak in the superconducting transition temperature of the nonmagnetic topological line-nodal material CaSb2 under pressure

2021/08/172021/08/31

Investigating the pressure dependence of the superconducting (SC) transition temperature Tc is crucial for understanding the SC mechanism. Herein, we report on the pressure dependence of Tc in the nonmagnetic topological line-nodal material CaSb2, based on measurements of electric resistance and alternating current magnetic susceptibility. Tc initially increases with increasing pressure and peaks at ∼ […]

Observation of s-wave superconductivity in CaSb₂

2021/07/302021/07/30

CaSb2 has a crystal structure with a special arrangement called “non-symmorphic’’. Due to this structure, it is expected that the bulk electronic energy bands have four-fold degeneracy along a line in the momentum space, which is called Dirac line node. In 2020, we discovered that CaSb2 exhibits superconductivity. Much attention has been paid to the […]

Anisotropic response of spin susceptibility in the superconducting state of UTe2 probed with 125Te−NMR measurement

2021/03/262021/03/26

To investigate spin susceptibility in a superconducting (SC) state, we measured the 125Te-nuclear magnetic resonance (NMR) Knight shifts at magnetic fields (H) up to 6.5 T along the b and c axes of single-crystal UTe2, a promising candidate for a spin-triplet superconductor. In the SC state, the Knight shifts along the b and c axes (Kb and Kc, respectively) decreased slightly and the decrease in Kb was almost […]

The alignment pattern of nematic superconductivity has been successfully controlled

2020/08/242020/08/25

In consumer liquid-crystal displays, “nematic” liquid-crystals, in which bar-shaped molecules align along a certain direction, are utilized. Configuration of this molecular alignment can be controlled by an applied voltage, to change the light transparency of each pixel. Recently, “nematic superconductivity”, which is analogous to nematic liquid-crystals, has been discovered. Superconductivity, the phenomenon characterized by the […]

Magnetic-Field Dependence of Novel Gap Behavior Related to the Quantum-Size Effect

2020/08/032020/08/18

195Pt-NMR measurements of Pt nanoparticles with a mean diameter of 4.0 nm were performed in a high magnetic field of approximately μ0H=23.3 T to investigate the low-temperature electronic state of the nanoparticles. The characteristic temperature T∗, below which the nuclear spin-lattice relaxation rate 1/T1 deviates from the relaxation rate of the bulk, shows a magnetic-field dependence. This dependence supports the […]