Tohoku University · Physics and Astronomy
Professor Takemi Kato's research lab specializes in the electronic structure and quantum phenomena of quantum materials, with a focus on kagome superconductors AV₃Sb₅ (A = K, Rb, Cs). The lab employs advanced angle-resolved photoemission spectroscopy (ARPES), including microfocused and temperature-dependent techniques, to investigate electron correlation, charge density wave order, superconductivity, and surface polarity. Key research directions include understanding the interplay between topology, electron correlation, and electronic order in kagome lattices, as well as the role of surface termination and doping in tuning quantum phases. The lab also explores exotic phenomena such as band folding, Fermi surface reconstruction, and large magneto-optical responses in correlated materials.
Figures are computed from collected data and may differ slightly.
Abstract Kagome lattices offer a fertile ground to explore exotic quantum phenomena associated with electron correlation and band topology. The recent discovery of superconductivity coexisting with charge-density wave (CDW) in the kagome metals KV 3 Sb 5 , RbV 3 Sb 5 , and CsV 3 Sb 5 suggests an intriguing entanglement of electronic order and superconductivity. However, the microscopic origin of CDW, a key to understanding the superconducting mechanism and its possible topological nature, remain
Kagome metals AV_{3}Sb_{5} (A=K, Rb, and Cs) exhibit a characteristic superconducting ground state coexisting with a charge density wave (CDW), whereas the mechanisms of the superconductivity and CDW have yet to be clarified. Here we report a systematic angle-resolved photoemission spectroscopy (ARPES) study of Cs(V_{1-x}Nb_{x})_{3}Sb_{5} as a function of Nb content x, where isovalent Nb substitution causes an enhancement of superconducting transition temperature (T_{c}) and the reduction of CDW
Polar surface and interface play pivotal roles for realizing exotic properties of materials, and search for such polar states is of crucial importance for expanding materials' functionality. Here we report microfocused angle-resolved photoemission spectroscopy of ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$, a member of recently discovered kagome superconductors $A{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$ ($A$ = K, Rb, and Cs) and show evidence for the polar nature of the cleaved surface which is characterize
Recently discovered kagome superconductors $A{\text{V}}_{3}{\text{Sb}}_{5}$ $(A=\mathrm{K}, \mathrm{Rb}, \mathrm{Cs})$ exhibit exotic bulk and surface physical properties such as charge density wave (CDW) and chirality, whereas their origins remain unresolved. By using microfocused angle-resolved photoemission spectroscopy, we discovered that $A{\text{V}}_{3}{\text{Sb}}_{5}$ commonly exhibits two distinct polar surfaces depending on the termination: electron- and hole-doped ones for the $A$ and
The magnetization and magneto-optical Kerr spectra of ordered MnPt3 alloy films were investigated. The films were prepared by annealing Mn/Pt multilayers at a temperature of 800°C for 30 minutes. It was found that the MnPt3 alloy films exhibit very large magneto-optical Kerr rotation, which reaches a maximum value of -1.1 deg at 1.24 eV. It is suggested that the large Kerr rotation is due not to enhancement by plasma resonance but to strong interband transitions.
Kagome metals AV3Sb5 (A = K, Rb, and Cs) exhibit a characteristic superconducting ground state coexisting with charge-density wave (CDW), whereas the mechanisms of the superconductivity and CDW have yet to be clarified. Here we report a systematic ARPES study of Cs(V1-xNbx)3Sb5 as a function of Nb content x, where isovalent Nb substitution causes an enhancement of superconducting transition temperature (Tc) and the reduction of CDW temperature (TCDW). We found that the Nb substitution shifts the
Applying lattice strain to thin films, a critical factor to tailor their properties such as stabilizing a structural phase unstable at ambient pressure, generally necessitates heteroepitaxial growth to control the lattice mismatch with substrate. Therefore, while homoepitaxy, the growth of thin film on a substrate made of the same material, is a useful method to fabricate high-quality thin films, its application to studying strain-induced structural phases is limited. Contrary to this general be
The magnetic and magneto-optical properties have been investigated for ordered (Mn1−xFex)Pt3 alloy (0<x<0.6) films, prepared by annealing (Mn-Fe)/Pt multilayer films at 800 °C. The Kerr spectrum of the MnPt3 film had a large negative peak value of −1.18° at 1.24 eV, and showed a small positive peak around 3.2 eV. With increasing Fe content x, the peak value at 1.24 eV decreased in magnitude and the position of the peak shifted towards lower energy side. Furthermore, another peak ap
We tried to control the magnetic anisotropy of a high-frequency carrier-type magnetic field sensor by varying the shape of the magnetic film instead of the induced anisotropy. We confirmed that the impedance of the sensor was changed by applying a magnetic field, and showed that the properties of the sensor could be controlled through the design of the magnetic film’ s shape.
Recently discovered kagome superconductors AV3Sb5 (A = K, Rb, Cs) exhibit exotic bulk and surface physical properties such as charge-density wave (CDW) and chirality, whereas their origins remain unresolved. By using micro-focused angle-resolved photoemission spectroscopy, we discovered that AV3Sb5 commonly exhibits two distinct polar surfaces depending on the termination; electron- and hole-doped ones for the A- and Sb-termination, respectively. We observed that the kagome-derived band shows a
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