arXiv subjects

K. Omura

Publications and source records attributed to K. Omura.

3 recordsLinked to original sources

arXiv2012

Magnetic phase diagram of the frustrated S=1/2 chain magnet LiCu_2O_2

We present the results of the magnetization and dielectric constant measurements on untwinned single crystal samples of the frustrated S=1/2 chain cuprate LiCu_2O_2. Novel magnetic phase transitions were observed. A spin flop transition of the spiral spin plane was observed for the field orientations H||a,b. The second magnetic transition was observed at H~15 T for all three principal field directions. This high field magnetic phase is discussed as a collinear spin-modulated phase which is expected for an S=1/2 nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic chain system.

cond-mat.str-el↗

arXiv2011

Microscopic Magnetic Nature of the Quasi-one-Dimensional Antiferromagnet BaCo2V2O8

The title compound belongs to a wide group of quasi-one-dimensional (Q1D) antiferromagnets (AF) and its Co2+ ions form Q1D screw-chains along the c-axis. We here present the first investigation of the microscopic magnetic nature of a single crystalline BaCo2V2O8 sample using μ+SR. Our data reveal the presence of several clear muon frequencies below TN indicating the onset of a long-range order. Above 5 K, the μ+SR spectra is well fitted to a simple power-exponential relaxing function. The temperature dependence of the relaxation-rate (λ) as well as the power (n) display a clear anomaly around T = 44 K, indicating the onset of short-range 1D correlations.

cond-mat.str-el↗

arXiv2010

New high magnetic field phase of the frustrated $S=1/2$ chain compound LiCuVO$_4$

Magnetization of the frustrated $S=1/2$ chain compound LiCuVO$_4$, focusing on high magnetic field phases, is reported. Besides a spin-flop transition and the transition from a planar spiral to a spin modulated structure observed recently, an additional transition was observed just below the saturation field. This newly observed magnetic phase is considered as a spin nematic phase, which was predicted theoretically but was not observed experimentally. The critical fields of this phase and its dM/dH curve are in good agreement with calculations performed in a microscopic model (M. E. Zhitomirsky and H. Tsunetsugu, preprint, arXiv:1003.4096v2).

cond-mat.str-el↗