The University of Tokyo · Physics and Astronomy
Professor Yukako Fujishiro's research lab specializes in topological quantum materials and emergent electromagnetic phenomena in quantum materials, with a focus on chiral magnets and spin textures such as magnetic skyrmions and hedgehogs. The lab investigates the interplay between electron correlation, spin topology, and transport properties, particularly through advanced experimental techniques like neutron scattering, Lorentz microscopy, and high-field transport measurements. Key research directions include the manipulation of topological spin textures, the origin of giant anomalous Hall effects, and the discovery of novel quantum phases under extreme conditions such as high pressure and magnetic fields. The lab also explores new materials platforms, including transition metal silicides and thin films, for spintronics and topological quantum devices.
Figures are computed from collected data and may differ slightly.
Manipulating topological spin textures is a key for exploring unprecedented emergent electromagnetic phenomena. Whereas switching control of magnetic skyrmions, e.g., the transitions between a skyrmion-lattice phase and conventional magnetic orders, is intensively studied towards development of future memory device concepts, transitions among spin textures with different topological orders remain largely unexplored. Here we develop a series of chiral magnets MnSi<sub>1-x</sub>Ge<sub>x</sub>, ser
The electrical Hall effect can be significantly enhanced through the interplay of the conduction electrons with magnetism, which is known as the anomalous Hall effect (AHE). Whereas the mechanism related to band topology has been intensively studied towards energy efficient electronics, those related to electron scattering have received limited attention. Here we report the observation of giant AHE of electron-scattering origin in a chiral magnet MnGe thin film. The Hall conductivity and Hall an
Spin structures with a non-trivial topology can emerge through the complex interplay of underlying magnetic interactions. Representative examples are magnetic skyrmions and hedgehogs observed in various materials. Although the most typical size of a skyrmion is 10–100 nm, there has been remarkable progress in the discovery of ultra-small (&lt;3 nm) skyrmions and hedgehogs in the last few years. The dense topological spin crystals not only hold promise for technological applications but also
The electrical Hall effect can be significantly enhanced through the interplay of the conduction electrons with magnetism, which is known as the anomalous Hall effect (AHE). Whereas the mechanism related to band topology has been intensively studied towards energy efficient electronics, those related to electron scattering have received limited attention. Here we report the observation of giant AHE of electron-scattering origin in a chiral magnet MnGe thin film. The Hall conductivity and Hall an
Transition metal monosilicides exhibit diverse physical properties depending on their crystal structures. Regarding IrSi, only the MnP-type orthorhombic form has been known so far. In this paper, the authors report a successful synthesis of a monoclinic phase through high-pressure high-temperature treatment above 25 GPa, while the theoretically predicted B20-type cubic structure has not been identified up to 48 GPa. Magneto-transport measurements reveal a semimetallic nature of the monoclinic fo
The authors reveal here anomalous charge transport upon melting of chiral spin orders, such as helical and skyrmion spin textures, in the itinerant chiral magnet FeGe. Under high pressure, significant modifications in the electronic structure induce a metal-to-semiconductor transition. Remarkably, a spontaneous anomalous Hall effect is observed in the short-range-ordered chiral spin ground state ($P$= 20--30 GPa) beyond the quantum phase transition. This macroscopic time-reversal symmetry breaki
Quantum states characterized by nontrivial topology produce interesting electrodynamics and versatile electronic functionalities. One source for such remarkable phenomena is emergent electromagnetic field, which is the outcome of interplay between topological spin structures with scalar spin chirality and conduction electrons. However, it has scarcely been exploited for emergent function related to heat-electricity conversion. Here we report an unusually enhanced thermopower by application of ma
A plethora of correlated and exotic metallic states have been identified on the border of itinerant magnetism, where the long-range spin texture is melted by tuning the magnetic transition temperature (T$_C$) towards zero, referred to as the quantum phase transition (QPT). So far, the study of QPT in itinerant magnets has mainly focused on low-T$_C$ materials (i.e., typically T$_C$ ~ 10 K) where the modification of electronic band structure is subtle, and only makes a small contribution to the Q
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