Search

Since the discovery of the anomalous Hall effect (AHE), the anomalous Hall conductivity (AHC) has been thought to be zero when there is no net magnetization. However, the recently found relation between the intrinsic AHE and the Berry curvature predicts other possibilities, such as a large AHC in non-colinear antiferromagnets with no net magnetization but net Berry curvature. Vice versa, the AHE in principle could be tuned to zero, irrespective of a finite magnetization. Here, we experimentally investigate this possibility and demonstrate that, the symmetry elements of Heusler magnets can be changed such that the Berry curvature and all the associated properties are switched while leaving the magnetization unaffected. This enables us to tune the AHC from 0 {\Omega}-1cm-1 up to 1600 {\Omega}-1cm-1 with an exceptionally high anomalous Hall angle up to 12 %, while keeping the magnetization same. Our study shows that the AHC can be controlled by selectively changing the Berry curvature distribution, independent of the magnetization., Comment: Published in Physical Review X. 16 pages, 5 figures

YSrCrO4 is first synthesized and found to be a hettotype of the K2NiF4 structure, although the combination of Y and Sr ions in K2NiF4-type oxides is very rare. The space group of the compound is determined to be orthorhombic Pccn by the electron diffraction and the powder X-ray diffraction. Magnetic and dielectric properties of the compound, together with LaSrCrO4, YCaCrO4 and A2MnO4 (A = Sr and Ca), are investigated. YSrCrO4 shows two-dimensional (2D) spin correlations and a canted antiferromagnetic (AF) ordering. With increasing distortion of the crystal structure, 2D spin correlations and the AF transition temperature decrease, while spontaneous magnetization increases. From the multi-frequency electron spin resonance (ESR) measurements, the g-values of the paramagnetic state are estimated to be 1.976, 1.978 and 1.976 for YSrCrO4, LaSrCrO4 and YCaCrO4, respectively. Evidence of AF ordering of the Cr oxides is obtained microscopically from ESR. The dielectric measurements suggest the existence of in-gap states, while no magneto-dielectric coupling was observed in the above compounds.

In order to elucidate the magnetic ground state of Sr2VO4, we have measured muon spin rotation and relaxation (mu+SR) spectra of a powder sample in the temperature range between 1.8 and 140 K. As a result, we have clarified that the transition at 105 K is not magnetic but structural and/or electric in origin and found the appearance of static antiferromagnetic (AF) order below 8 K. Moreover, the distribution of the internal AF field was found to be very broad, even at the lowest temperature measured. These results are consistent with the formation of an orbital-stripe order with collinear AF order for the magnetic ground state of Sr2VO4.

Facilitating vocabulary knowledge is a challenging aspect for language learners. Although current corpus-based reference tools provide authentic contextual clues, the plain text format is not conducive to fully illustrating some lexical phenomena. Thus, this paper proposes GLANCE 1 , a text visualization tool, to present a large amount of lexical phenomena using charts and graphs, aimed at helping language learners understand a word quickly and intuitively. To evaluate the effectiveness of the system, we designed interfaces to allow comparison between text and graphics presentation, and conducted a preliminary user study with ESL students. The results show that the visualized display is of greater benefit to the understanding of word characteristics than textual display.

It is found that samples of LaCu3Ru4O12 have a large amount of defects at Ru and O sites. High-pressure synthesis reduces the amount of defects. The samples made under high pressure reveal the intrinsic behavior of magnetic susceptibility of the compound. It shows the Curie–Weiss-like behavior above approximately 130 K and a saturation at χ = 5.6 × 10−3 emu/mol below approximately 30 K.

In order to elucidate the magnetic nature of K2NiF4-type 3d transition metal oxides, we have measured μ+SR spectra for Sr2VO4, LaSrVO4, and Sr2CrO4 using powder samples. ZF- and wTF-μ+SR measurements propose that Sr2VO4 enters into the static antiferromagnetic (AF) order phase below 8 K. In addition, TF-μ+SR measurements evidence that the transition at 105 K is not magnetic but structural and/or electronic in origin. For LaSrVO4, static long-range order has not been observed down to 20 K, while, as T decreases from 145 K, wTF asymmetry starts to decrease below 60 K, suggesting the appearance and evolution of localized magnetic moments below 60 K. For Sr2CrO4, by contrast, both ZF- and wTF-μ+SR have confirmed the presence of antiferromagnetic order below 117 K, as predicted in the χ(T) curve.