Long magnetic penetration depth observed in Sr3−xSnO

Antiperovskite oxide superconductor Sr3−xSnO was measured by a method called muon spin rotation (μSR). It became clear that the magnetic field penetration depth is abnormally long. Sr3−xSnO is a superconductor discovered in our laboratory in 2016. It is the first superconductor in the antiperovskite oxide, and the possibility of topological superconductivity has been theoretically proposed. […]

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“Diamagnetic” signals can appear due to localised heating

Magnetic differential measurements In order to perform magnetisation measurements, it is usually necessary to put a sample onto a sample holder. If the holder magnetization is exactly zero, it is straightforward to extract the sample magnetisation. However, it is practically impossible to bring the holder magnetisation completely to zero. Thus, it is common to use […]

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Discovery of superconductivity in CaSb2

In CaSb2 , the calcium and antimony atoms are arranged in a special arrangement called “non-conformal”. Since atoms are arranged periodically in a crystal, if one atom moves in parallel so that it overlaps with the next atom, other atoms also overlap with the next atom, resulting in the same structure as the original. I will. In addition to […]

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Variation in Superconducting Symmetry with Pressure on a Noncentrosymmetric Superconductor

We performed 185/187Re nuclear quadrupole resonance (NQR) measurements under pressure to investigate the superconducting properties of noncentrosymmetric superconductor Cd2Re2O7 under various crystal structures. The pressure dependence of superconducting transition temperature Tc determined through ac susceptibility measurements is consistent with the results of previous resistivity measurements [Kobayashi et al., J. Phys. Soc. Jpn. 80, 023715 (2011)]. Below 2.2 GPa, in the nuclear […]

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NMR-based gap behavior related to the quantum size effect

It is theoretically predicted that the energy level of nanoparticles that have a reduced diameter down to the nanometer size will be discrete in energy level, unlike bulk materials in which energy exists continuously. This effect is called the quantum size effect or the Kubo effect after the name of Prof. Ryogo Kubo. Although it has been […]

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Observation of anion states of tin in Sr3-xSnO

In an antiperovskite oxide Sr3SnO, an anionic state is naively expected for tin such as (Sr2+)3Sn4-O2-. Since tin is a metallic element and tends to be cations like Sn2+ and Sn4+, the “charge-inverted” state Sn4− is unusual and very rare in oxides. However, it has not been experimentally investigated how many electrons tin actually possesses in antiperovskite oxides. We made […]

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Superconductivity with Spin Degrees of Freedom

Superconductivity is known as a phenomenon where electrical resistance becomes zero when a substance is cooled to a low temperature. In superconductivity, two electrons form a paired state (superconducting pair), and in most cases the spins of the two electrons are antiparallel (called the spin singlet state). Therefore, superconductivity is destroyed under a strong magnetic field. However, the […]

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Superconductivity near the ferromagnetic quantum critical of UCoGe

UCoGe is one of the ferromagnetic superconductors that show a superconducting transition inside ferromagnetism, and it is thought that the quantum criticality of ferromagnetism is related to superconductivity. In fact, it is known that even if the ferromagnetism disappears by the application of hydrostatic pressure of about 1 GPa (10,000 atmospheric pressure), the superconducting phase still […]

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