arXiv subjects

Pukun Tan

Publications and source records attributed to Pukun Tan.

4 recordsLinked to original sources

arXiv2025

Tunable interplay of orbital and spin magnetization in trigonal tellurium

Orbital effects, despite their fundamental significance and potential to engender novel physical phenomena and enable new applications, have long been underexplored compared to their spin counterparts. Recently, surging interest in the orbital degree of freedom has led to the discovery of a plethora of orbital-related effects, underscoring the need for a deeper understanding of their roles in quantum materials. Here, we report systematic experimental evidence consistent with orbital magnetization and spontaneous rotational symmetry breaking in trigonal Tellurium, an elemental semiconductor with a unique helical crystal structure that serves as a natural platform for investigating orbital effects. Detailed angular dependent linear and nonlinear magnetotransport measurements, supported by symmetry-guided Boltzmann transport analysis, support the interpretation of coexistence of current-induced spin polarization and orbital magnetization. With the goal of disentangling the interplay between spin and orbital degrees of freedom through electrostatic gating, this work establishes a general framework for understanding orbital magnetization in chiral crystals and beyond, paving the way for its utilization in orbitronics and spintronics.

cond-mat.mtrl-sci↗

arXiv2024

Ultralow Voltage Operation of p- and n-FETs Enabled by Self-Formed Gate Dielectric and Metal Contacts on 2D Tellurium

The ongoing demand for more energy-efficient, high-performance electronics is driving the exploration of innovative materials and device architectures, where interfaces play a crucial role due to the continuous downscaling of device dimensions. Tellurium (Te), in its two-dimensional (2D) form, offers significant potential due to its high carrier mobility and ambipolar characteristics, with the carrier type easily tunable via surface modulation. In this study, we leverage atomically controlled material transformations in 2D Te to create intimate junctions, enabling near-ideal field-effect transistors (FETs) for both n-type and p-type operation. A NiTex-Te contact provides highly transparent interfaces, resulting in low contact resistance, while the TiOx-Te gate dielectric forms an ultraclean interface with a capacitance equivalent to 0.88 nm equivalent oxide thickness (EOT), where the quantum capacitance of Te is observed. Subthreshold slopes (SS) approach the Boltzmann limit, with a record-low SS of 3.5 mV/dec achieved at 10 K. Furthermore, we demonstrate 2D Te-based complementary metal-oxide-semiconductor (CMOS) inverters operating at an ultralow voltage of 0.08 V with a voltage gain of 7.1 V/V. This work presents a promising approach to forming intimate dielectric/semiconductor and metal/semiconductor junctions for next-generation low-power electronic devices.

physics.app-ph↗

arXiv2023

Tunable Circular Photogalvanic and Photovoltaic Effect in 2D Tellurium with Different Chirality

Chirality arises from the asymmetry of matters, where two counterparts are the mirror image of each other. The interaction between circular-polarization light and quantum materials is enhanced in chiral space groups due to the structural chirality. Tellurium (Te) possesses the simplest chiral crystal structure, with Te atoms covalently bonded into a spiral atomic chain (left- or right-handed) with a periodicity of three. Here, we investigate the tunable circular photo-electric responses in 2D Te field-effect transistor with different chirality, including the longitudinal circular photogalvanic effect induced by the radial spin texture (electron-spin polarization parallel to the electron momentum direction) and the circular photovoltaic induced by the chiral crystal structure (helical Te atomic chains). Our work demonstrates the controllable manipulation of the chirality degree of freedom in materials.

cond-mat.mes-hall↗

arXiv2022

Tunable Chirality-dependent Nonlinear Electrical Responses in 2D Tellurium

Tellurium (Te) is an elemental semiconductor with a simple chiral crystal structure. Te in a two-dimensional (2D) form synthesized by solution-based method shows excellent electrical, optical, and thermal properties. In this work, the chirality of hydrothermally grown 2D Te is identified and analyzed by hot sulfuric acid etching and high-angle tilted high-resolution scanning transmission electron microscopy. The gate-tunable nonlinear electrical responses, including the nonreciprocal electrical transport in the longitudinal direction and the nonlinear planar Hall effect in the transverse direction, are observed in 2D Te under a magnetic field. Moreover, the nonlinear electrical responses have opposite signs in left- and right-handed 2D Te due to the opposite spin polarizations ensured by the chiral symmetry. The fundamental relationship between the spin-orbit coupling and the crystal symmetry in two enantiomers provides a viable platform for realizing chirality-based electronic devices by introducing the chirality degree of freedom into electron transport.

cond-mat.mtrl-sci↗