arXiv subjects

Shaohua Yan

Publications and source records attributed to Shaohua Yan.

21 records · Page 2Linked to original sources

arXiv2021

Superconductivity and normal-state properties of kagome metal RbV3Sb5 single crystals

We report the discovery of superconductivity and detailed normal-state physical properties of RbV3Sb5 single crystals with V kagome lattice. RbV3Sb5 single crystals show a superconducting transition at Tc ~ 0.92 K. Meanwhile, resistivity, magnetization and heat capacity measurements indicate that it exhibits anomalies of properties at T* ~ 102 - 103 K, possibly related to the formation of charge ordering state. When T is lower than T*, the Hall coefficient RH undergoes a drastic change and sign reversal from negative to positive, which can be partially explained by the enhanced mobility of hole-type carriers. In addition, the results of quantum oscillations show that there are some very small Fermi surfaces with low effective mass, consistent with the existence of multiple highly dispersive Dirac band near the Fermi energy level.

cond-mat.supr-con↗

arXiv2020

Tunable layered-magnetism-assisted magneto-Raman effect in a two-dimensional magnet $\mathrm{CrI_3}$

We use a combination of polarized Raman spectroscopy experiment and model magnetism-phonon coupling calculations to study the rich magneto-Raman effect in the two-dimensional (2D) magnet $\mathrm{CrI_3}$. We reveal a novel layered-magnetism-assisted phonon scattering mechanism below the magnetic onset temperature, whose Raman excitation breaks time-reversal symmetry, has an antisymmetric Raman tensor, and follows the magnetic phase transitions across critical magnetic fields, on top of the presence of the conventional phonon scattering with symmetric Raman tensors in $N$-layer $\mathrm{CrI_3}$. We resolve in data and by calculations that the 1st-order $A_g$ phonon of monolayer splits into a $N$-fold multiplet in $N$-layer $\mathrm{CrI_3}$ due to the interlayer coupling ($N$>=2) and that the phonons with the multiple show distinct magnetic field dependence because of their different layered-magnetism-phonon coupling. We further find that such a layered-magnetism-phonon coupled Raman scattering mechanism extends beyond 1st-order to higher-order multi-phonon scattering processes. Our results on magneto-Raman effect of the 1st-order phonons in the multiplet and the higher-order multi-phonons in $N$-layer $\mathrm{CrI_3}$ demonstrate the rich and strong behavior of emergent magneto-optical effects in 2D magnets and underlines the unique opportunities of new spin-phonon physics in van der Waals layered magnets.

cond-mat.mtrl-sci↗

arXiv2018

Tuning the Dzyaloshinskii-Moriya Interaction in Pt/Co/MgO heterostructures through MgO thickness

The interfacial Dzyaloshinskii-Moriya interaction (DMI) in the ferromagnetic/heavy metal ultra-thin film structures , has attracted a lot of attention thanks to its capability to stabilize Neel-type domain walls (DWs) and magnetic skyrmions for the realization of non-volatile memory and logic devices. In this study, we demonstrate that magnetic properties in perpendicularly magnetized Ta/Pt/Co/MgO/Pt heterostructures, such as magnetization and DMI, can be significantly influenced through both the MgO and the Co ultrathin film thickness. By using a field-driven creep regime domain expansion technique, we find that non-monotonic tendencies of DMI field appear when changing the thickness of MgO and the MgO thickness corresponding to the largest DMI field varies as a function of the Co thicknesses. We interpret this efficient control of DMI as subtle changes of both Pt/Co and Co/MgO interfaces, which provide a method to investigate ultra-thin structures design to achieve skyrmion electronics.

physics.app-ph↗