Magnetic anisotropy on the single crystal UNi4B probed by 11B NMR

11B-NMR Investigation for Crystal Structure in Antiferromagnet UNi4B

“…Recently, we have succeeded to observe the 11 B-NMR spectrum for a single crystalline sample. In our previous study, we performed field-sweep NMR measurements and reported that the well split 11 B-NMR spectrum with its linewidth of 400 G due to the nuclear quadrupole interaction was observed for the magnetic field parallell to hexagonal [1120]-and [0001]-axes [12]. Here, the nuclear quadrupole frequency and asymmetry parameter were obtained to be ν Q = 0.24 ± 0.02 and η = 0.…”

“…11 B-NMR measurements were carried out at T =50 K using a Fast-Fourier-Transform (FFT)-NMR technique of spin-echo signal for the constant magnetic field. In order to avoid the spectral broadening of the magnetic dipolar interaction, NMR measurement was carried out at 1 T, which is lower than 5 T in the previous measurement [12]. In addition, the width of excitation π/2 and π pulses were 0.8 µs and 1.5µs, respectively.…”

Zero-field current-induced Hall effect in ferrotoroidic metal

“…Besides the above two possibilities, the anomaly at T * ∼ 0.33 K of unknown origin in measurements of resistivity and specific-heat for UNi 4 B [42,43] may explain the above-mentioned inconsistency. Very recently, it has been suggested that this anomaly does not reflect the additional modification of magnetic structure [33], but the contribution of electric-quadrupoles of the paramagnetic 1/3 U ions [44][45][46]. The quadrupolar contributions in the ferrotoroidic ordered state seem to affect the drastic enhancement of current-induced magnetization with decreasing temperature, especially below ∼ 5 K where the sudden softning of transverse ultrasonic mode C 66 is observed [46] in addition to the reduction of χ b [19] and ρ aa [31] as well as the gradual enhancement of specific heat divided by temperature [31] and thermal expansion along the c axis [47].…”