Spontaneous topological Hall effect induced by non-coplanar antiferromagnetic order in intercalated van der Waals materials

Takagi, Hirotaka*; Takagi, Rina*; Minami, Susumu*; Nomoto, Takuya*; Oishi, Kazuki*; Suzuki, Michito*; Yanagi, Yuki*; Hirayama, Motoaki*; Khanh, N.*; Karube, Kosuke*; et al.

Nature Physics, 19(7), p.961 - 968, 2023/07

https://doi.org/10.1038/s41567-023-02017-3

Ferromagnetic crossover within the ferromagnetic order of UTe

Opletal, P.; Sakai, Hironori; Haga, Yoshinori; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Kambe, Shinsaku; Tokunaga, Yo

Journal of the Physical Society of Japan, 92(3), p.034704_1 - 034704_5, 2023/03

https://doi.org/10.7566/JPSJ.92.034704

We investigate the physical properties of a single crystal of uranium telluride UTe. We have confirmed that UTe crystallizes in the hexagonal structure with three nonequivalent crystallographic uranium sites. The paramagnetic moments are estimated to be approximately 1 per the uranium site, assuming a uniform moment on all the sites. A ferromagnetic phase transition occurs at = 48 K, where the in-plane magnetization increases sharply, whereas the out of-plane component does not increase significantly. With decreasing temperature further below under field-cooling conditions, the out-of-plane component increases rapidly around T= 26 K. In contrast, the in-plane component hardly changes at T. Specific heat measurement indicates no -type anomaly around T, so this is a cross-over suggesting a reorientation of the ordering moments or successive magnetic ordering on the part of the multiple uranium sites.

Development of a miniature electromagnet probe for the measurement of local velocity in heavy liquid metals

Ariyoshi, Gen; Obayashi, Hironari; Sasa, Toshinobu

Journal of Nuclear Science and Technology, 59(9), p.1071 - 1088, 2022/09

https://doi.org/10.1080/00223131.2022.2030824

Electromagnetic induction method is one of the effective techniques for local velocity measurement in heavy liquid metals. Ricou and Vives' probe and Von Weissenfluh's probe are famous instrumentations using a permanent magnet. However, sensitivity and measurement volume of the probes show unexpected variation since demagnetization of the magnet is occurred by temperature increase up to the Curie temperature. In this study, electromagnetic probe incorporating a miniature electromagnet was newly developed to overcome such unexpected variation. The diameter and the length of the sensor was 6 mm and 155 mm, respectively. The sensitivity and the measurement volume of the probe were assessed by measurement of local velocity of flowing mercury in a square channel. To clarify the validity for the measured velocity profiles, numerical velocity profiles were calculated and compared with experiment. And the validity for the measured velocity profiles were confirmed by calculated result.

Single crystal growth and magnetic properties of noncentrosymmetric antiferromagnet MnIrSi

Onuki, Yoshichika*; Kaneko, Yoshio*; Aoki, Dai*; Nakamura, Ai*; Matsuda, Tatsuma*; Nakashima, Miho*; Haga, Yoshinori; Takeuchi, Tetsuya*

Journal of the Physical Society of Japan, 91(6), p.065002_1 - 065002_2, 2022/06

https://doi.org/10.7566/JPSJ.91.065002

Abrupt change in electronic states under pressure in new compound EuPtAl

Koizumi, Takatsugu*; Honda, Fuminori*; Sato, Yoshiki*; Li, D.*; Aoki, Dai*; Haga, Yoshinori; Gochi, Jun*; Nagasaki, Shoko*; Uwatoko, Yoshiya*; Kaneko, Yoshio*; et al.

Journal of the Physical Society of Japan, 91(4), p.043704_1 - 043704_5, 2022/04

https://doi.org/10.7566/JPSJ.91.043704

A Proposal of optimum calculation settings of continuous wavelet transform in magnetotelluric data processing

Ogawa, Hiroki; Hama, Yuki*; Asamori, Koichi; Ueda, Takumi*

Butsuri Tansa, 75, p.38 - 55, 2022/00

https://doi.org/10.3124/segj.75.38

In the magnetotelluric (MT) method, so as to identify the subsurface resistivity structure, the apparent resistivity and phase profiles are calculated by transforming time-series data into spectral data. The continuous wavelet transform (CWT) is well known as a new method of time-frequency analysis instead of the short-time Fourier transform. The CWT is superior in processing non-stationary wideband signals like the MT signal by adjusting the size of the wavelet according to the value of frequency. However, the calculation settings of the CWT, such as the type of basis function and the wavelet parameter, are often determined empirically because of the arbitrariness of the shape of the wavelet. Although there might be differences between the calculated MT responses and the true responses due to improper settings of the CWT, there are no detailed studies considering the effect of numerical errors derived from spectral transforms on MT data. In this study, focusing on the frequency band between 0.001 Hz and 1 Hz, we examined the optimum calculation settings of the CWT in processing MT data in terms of suppressing the numerical errors caused by the spectral transform of time-series data. We also show the validity of the proposed calculation settings by applying the CWT to MT survey data of different types. Superiority of the CWT with proposed settings is suggested especially when the signal-to-noise ratio of observed data is low. Consequently, the proposed calculation settings were confirmed to strike a balance between the resolutions of the time and frequency domains well and will therefore be effective in obtaining reliable MT responses.

Half-integer Shapiro steps in strong ferromagnetic Josephson junctions

Yao, Y.*; Cai, R.*; Yang, S.-H.*; Xing, W.*; Ma, Y.*; Mori, Michiyasu; Ji, Y.*; Maekawa, Sadamichi; Xie, X.-C.*; Han, W.*

Physical Review B, 104(10), p.104414_1 - 104414_6, 2021/09

https://doi.org/10.1103/PhysRevB.104.104414

Dependence of charge-exchange efficiency on cooling water temperature of a beam transport line

Yamamoto, Kazami; Hatakeyama, Shuichiro; Saha, P. K.; Moriya, Katsuhiro; Okabe, Kota; Yoshimoto, Masahiro; Nakanoya, Takamitsu; Fujirai, Kosuke; Yamazaki, Yoshio; Suganuma, Kazuaki

EPJ Techniques and Instrumentation (Internet), 8(1), p.9_1 - 9_9, 2021/07

https://doi.org/10.1140/epjti/s40485-021-00067-6

The 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.6310 variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.0810. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

Observation of longitudinal magnetic fluctuations at a first-order ferromagnetic quantum phase transition in UGe

Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Nakamura, Ai*; et al.

Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07

https://doi.org/10.7566/JPSJ.90.073707

Feasibility study of magnetic-domain observation by means of non-resonant magnetic X-ray diffraction

Inami, Toshiya*; Shobu, Takahisa; Ishii, Kenji*

IEEE Transactions on Magnetics, 57(3, Part2), p.6400105_1 - 6400105_5, 2021/03

https://doi.org/10.1109/TMAG.2020.3046006