Breakdown of Kubo relation in Pt-Cu nanoparticle

Nanoparticles were predicted to exhibit unique physical properties due to quantum size effects, but their identification remains difficult.According to Kubo’s theory, the gap size is inversely correlated with both the density of states at the Fermi energy and the number of atoms in the particle.Previously, we confirmed that the particle size and magnetic field dependence […]

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Superconducting spin reorientation in spin-triplet multiple superconducting phases of UTe2

Superconducting (SC) state has spin and orbital degrees of freedom, and spin-triplet superconductivity shows multiple SC phases because of the presence of these degrees of freedom. However, the observation of spin-direction rotation occurring inside the SC state (SC spin rotation) has hardly been reported. Uranium ditelluride, a recently found topological superconductor, exhibits various SC phases […]

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Gapless fermionic excitation in the antiferromagnetic state of ytterbium zigzag chain

The emergence of charge-neutral fermionic excitations in magnetic systems is one of the unresolved issues in recent condensed matter physics. This type of excitations has been observed in various systems, such as low-dimensional quantum spin liquids, Kondo insulators, and antiferromagnetic insulators. Here, we report the presence of a pronounced gapless spin excitation in the low-temperature […]

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

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 […]

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

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 […]

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Pairing interaction in superconducting UCoGe tunable by magnetic field

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 […]

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

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 ∼ […]

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