Koichi Kindo

1/3 Magnetization plateau in SrCu2(BO3)2 : Stripe order of excited triplets

High-field magnetization measurements up to 57 T have been performed at 0.08 K in a single crystal of a two-dimensional spin-gap material SrCu 2 (BO 3 ) 2 . We successfully observed the predicted plateau at 1/3 of the total magnetization around 50 T, in which the magnetic superstructure is characterized by a novel stripe order of triplets. The 1/3 plateau is much wider than the previously observed 1/4 and 1/8 plateaux.

Magnetic and Thermal Properties of CeIrIn5 and CeRhIn5

We studied the magnetic properties in a non-magnetic heavy-fermion compound CeIrIn 5 and an antiferromagnetic compound CeRhIn 5 with the tetragonal structure. High-field magnetization of CeIrIn 5 s...

Field-Induced Destruction of Heavy Fermion State in URu2Si2

High-field magnetization and magnetoresistance of URu 2 Si 2 single crystal are investigated up to 600 kOe. Three-step metamagnetic transitions are obtained with the transition fields of 358, 365 and 396 kOe at 1.3 K. The experimental results are explained quantitatively by introducing the model that the heavy Fermion state produced by the mixing of the f- and conduction electrons is destroyed by applying the field and that the exchange interactions between the recovered local f-electron magnetic moments on the uranium atom play an important role on the magnetic properties at high field. The frustration due to the exchange interactions induces the three-step metamagnetic transitions.

Magnetization ''Steps'' on a Kagome Lattice in Volborthite

Magnetic properties of the spin-1/2 kagome-like compound volborthite are studied using a high-quality polycrystalline sample. It is evidenced from magnetization and specific heat measurements that the spins on the kagome lattice still fluctuate at low temperature, down to T =60 mK that corresponds to 1/1500 of the nearest-neighbor antiferromagnetic interaction, exhibiting neither a conventional long-range order nor a spin gap. In contrast, 51 V NMR experiments revealed a sharp peak at 1 K in relaxation rate, which indicates that a certain exotic order occurs. Surprisingly, we have observed three “steps” in magnetization as a function of magnetic field, suggesting that at least four liquid-like or other quantum states exist under magnetic fields.

Upper Critical Fields of the 11-System Iron-Chalcogenide Superconductor FeSe0:25Te0:75

We have performed electrical resistivity measurements of a polycrystalline sample of FeSe 0.25 Te 0.75 , which exhibits superconductivity at T c ∼14 K, in magnetic fields up to 55 T to determine the upper critical field µ 0 H c2 . In this compound, very large slopes of µ 0 H c2 at the onset, the mid-point, the zero-resistivity temperatures on superconductivity are determined to be -13.7, -10.1, and -6.9 T/K, respectively. The observed µ 0 H c2 ( T )s of this compound are considerably smaller than those expected from the Werthamer–Helfand–Hohenberg model, manifesting the Pauli limiting behavior. These results suggest that this compound shows the spin-singlet pairing in the superconducting state.

Successive magnetic phase transitions inα−RuCl3: XY-like frustrated magnet on the honeycomb lattice

The layered compound

Unconventional upper- and lower-critical fields and normal-state magnetic susceptibility of the superconducting compound Na 0.35 CoO 2 ⋅ 1.3 H 2 O

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Magnetic and Superconducting Properties of LaIrSi3and CeIrSi3with the Non-centrosymmetric Crystal Structure

-RuCl

Magnetic properties of a pressure-induced superconductor UGe2

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Metamagnetic Behavior of the Heavy-Fermion Compound CeNi2Ge2.

is composed of a honeycomb lattice of magnetic Ru