arXiv subjects

Katsushi Hashimoto

Publications and source records attributed to Katsushi Hashimoto.

4 recordsLinked to original sources

arXiv2022

Spatially Resolving Electron Spin Resonance of $π$-Radical in Single-molecule Magnet

The spintronic properties of magnetic molecules have attracted significant scientific attention. Special emphasis has been placed on the qubit for quantum information processing. The single molecule magnet, bis(phthalocyaninato (Pc)) Tb(III) (TbPc2), is one of the best examined cases in which the delocalized π-radical electron spin of the Pc ligand plays the key role in reading and intermediating the localized Tb spin qubits. We utilized the electron spin resonance (ESR) technique implemented on scanning tunneling microscope (STM) and use it to measure local ESR of single TbPc2 molecule decoupled from the Cu(100) substrate by 2 monolayers NaCl film to identify the π-radical spin. We detected the ESR signal at the ligand positions at the resonance condition expected for the S = 1/2 spin. The results reveal that the π-radical electron is delocalized within the ligands and exhibits intramolecular coupling susceptible to the chemical environment.

quant-ph↗

arXiv2022

Even-denominator fractional quantum Hall state in conventional triple-gated quantum point contact

The even-denominator states have attracted considerable attention owing to their possible applications in future quantum technologies. In this letter, we first report a 3/2 diagonal resistance, indicating the existence of a 3/2 state in a nanometer-sized triple-gated quantum point contact (QPC) fabricated on a high-mobility (not ultra-high-mobility) single-layer two-dimensional (2D) GaAs wafer. The center gate plays a crucial role in realizing the QPC's 3/2 state. Our observation of the 3/2 state using a conventional QPC device, which is a suitable building block for semiconductor quantum devices, paves a new path for the development of semiconductor-based quantum technologies.

cond-mat.mes-hall↗

arXiv2020

Imaging disorder-induced scattering centers in quantum Hall incompressible strip

While the disorder-induced quantum Hall (QH) effect has been studied previously, the effect ofdisorder potential on microscopic features of the integer QH effect remains unclear, particularly forthe incompressible (IC) strip. In this research, a scanning gate microscope incorporated with thenonequilibrium transport technique is used to image the region of QH IC strip that emerges near thesample edge. It was found that different mobility samples with varying disorder potentials showedthe same spatial dependence of the IC strip on the filling factor (ν). In the low-mobility samplealone, scattering centers such, bright, dark and annular patterns, alternately appear within the IC strip. These observed patterns are ascribed to inter-LL scattering assisted by resonance tunnelingthrough an impurity bound state. It is concluded that disorder-induced scattering can be effectivelydetected using the applied technique in a low-mobility sample.

cond-mat.mes-hall↗

arXiv2004

Effects of Quantum-Well Inversion Asymmetry on Electron-Nuclear Spin Coupling in the Fractional Quantum Hall Regime

We examine effects of inversion asymmetry of a GaAs/Al0.3Ga0.7As quantum well (QW) on electron-nuclear spin coupling in the fractional quantum Hall (QH) regime. Increasing the QW potential asymmetry at a fixed Landau-level filling factor (nu) with gate voltages suppresses the current-induced nuclear spin polarization in the nu = 2/3 Ising QH ferromagnet, while it significantly enhances the nuclear spin relaxation at general nu. These findings suggest that mixing of different spin states due to the Rashba spin-orbit interaction strongly affects the electron-nuclear spin coupling.

cond-mat.mes-hall↗