arXiv subjects

Taesu Park

Publications and source records attributed to Taesu Park.

3 recordsLinked to original sources

arXiv2023

Optical transitions of a single nodal ring in SrAs$_3$: radially and axially resolved characterization

SrAs$_3$ is a unique nodal-line semimetal that contains only a single nodal ring in the Brillouin zone, uninterrupted by any trivial bands near the Fermi energy. We performed axis-resolved optical reflection measurements on SrAs$_3$ and observed that the optical conductivity exhibits flat absorption up to 129 meV in both the radial and axial directions, confirming the robustness of the universal power-law behavior of the nodal ring. Furthermore, in conjunction with model and first-principles calculations, the axis-resolved optical conductivity unveiled fundamental properties beyond the flat absorption, including the overlap energy of the topological bands, the spin-orbit coupling gap along the nodal ring, and the geometric properties of the nodal ring such as the average ring radius, ring ellipticity, and velocity anisotropy. In addition, our temperature-dependent measurements revealed a spectral weight transfer between intraband and interband transitions, indicating a possible violation of the optical sum rule within the measured energy range.

cond-mat.str-el↗

arXiv2020

Tailoring high-TN interlayer antiferromagnetism in a van der Waals itinerant magnet

Antiferromagnetic (AFM) van der Waals (vdW) materials provide a novel platform for synthetic AFM spintronics, in which the spin-related functionalities are derived from manipulating spin configurations between the layers. Metallic vdW antiferromagnets are expected to have several advantages over the widely-studied insulating counterparts in switching and detecting the spin states through electrical currents but have been much less explored due to the lack of suitable materials. Here, utilizing the extreme sensitivity of the vdW interlayer magnetism to material composition, we report the itinerant antiferromagnetism in Co-doped Fe4GeTe2 with TN ~ 210 K, an order of magnitude increased as compared to other known AFM vdW metals. The resulting spin configurations and orientations are sensitively controlled by doping, magnetic field, temperature, and thickness, which are effectively read out by electrical conduction. These findings manifest strong merits of metallic vdW magnets with tunable interlayer exchange interaction and magnetic anisotropy, suitable for AFM spintronic applications.

cond-mat.mtrl-sci↗

arXiv2020

Enhancement of Giant Rashba Splitting in BiTeI under Asymmetric Interlayer Interaction

We carry out density functional theory calculation to enhance the Rashba spin splitting (RSS) of BiTeI by modifying the interlayer interaction. It is shown that RSS increases as the Te layer approaches to adjacent Bi layer or the I layer recedes from the Bi layer. Our results indicate that the RSS can be sensitively increased by introducing a vacancy on the Te site to make effective Bi-Te distance shorter. It is also found that the difference of Te p orbital character between two spin-split bands increases when the RSS is developed along crystal momentum, which supports asymmetric interlayer interaction in the spin-split bands. Our work suggests that the modification of interlayer interaction is an effective approach in the modeling of the RSS in BiTeI and other layered materials.

cond-mat.mes-hall↗