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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Universal relation between superconductivity and antiferromagnetic fluctuations in iron-based superconductor BaFe 2  (As 1- x P x ) 2 

The iron-based superconductor BaFe 2 As 2 suppresses antiferromagnetism by various dopings and pressures and develops superconductivity. We applied pressure to BaFe 2 (As 1- x P x ) 2 with part of As replaced by equivalent P and searched for the essential parameters that govern the superconducting transition temperature by changing two parameters, the P substitution amount and the pressure. As shown in the figure, the superconducting transition temperature at various […]

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Spin triplet superconductivity of UCoGe in the paramagnetic region under pressure.

UCoGe is a unique substance that exhibits a superconducting transition inside ferromagnetism. Based on our group’s previous studies, it is considered that large spin fluctuations in the c- axis direction (states close to the ferromagnetic transition) are essential for the development of superconductivity in this system. Since it has a close relationship with ferromagnetism, it has been expected that in […]

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Half-integer quantum fluxoid state in Sr2RuO4 microrings

The ruthenium oxide superconductor Sr2RuO4 is considered to be in the spin triplet equal spin state from nuclear magnetic resonance (NMR) experiments. It is known that fluxoids are quantized in units of magnetic flux quantum Φ0 in superconductors, but in such superconducting states, wavefunctions also have spin degrees of freedom compared to orbital degrees of freedom, so flaxoids There Fai 0 will be […]

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