Two-dimensional (2D) magnets hold promise for spintronics but still face challenges regarding limited magnetic tunability and air stability. Here, we demonstrate an effective oxygen plasma treatment strategy that simultaneously modulates magnetism and enhances the air stability of 1T-CrTe2 films. Microstructural characterizations reveal a depth-dependent progressive oxygen induced reconstruction process, in which oxygen substitution induces local Cr–Te–O structural rearrangements that are more pronounced near the surface and gradually extend toward the inner layers with increasing treatment duration. Theoretical calculations combined with magnetic measurements suggest that the effective oxidation level regulates interlayer magnetic coupling, leading to an evolution from a FiM-related step-like magnetic transition behavior to a FM-dominated magnetic response. Significantly, the oxygen-doped 1T-CrTe2 exhibits robust environmental stability, retaining room-temperature magnetism even after long-term ambient exposure. This work presents a dual-purpose approach for engineering robust, tunable 2D materials for future spintronic applications.
The research about two-dimensional van der Waals magnetic materials has advanced the 22 breakthroughs in ultrathin magnetic devices. We experimentally demonstrate that single-crystal 23 N-face AlN polar substrate can program layer-number-parity-dependent magnetic multistates and 24 their evolution sequence in few-layer CrI3. In odd-layer samples, as 5L-CrI3/AlN, when μ0H 25 sweeps from 3 to −3 T, the reflective magnetic circular dichroism signal evolves through distinct 26 magnetic multistates (+5 → –1 → +1 → –5), where +1 corresponds to the moment of a spin-up 27 monolayer. Thereby, we vertically program novel magnetic ground states and their evolution 28 sequence via a simplified heterointerface. Our first-principles calculations attribute this effect to 29 interfacial hole doping: it globally reconfigures the magnetic ground state of odd-layer CrI3 to a 30 novel ferrimagnetic order, and spatially differentiates the interlayer exchange and magnetic 31 anisotropy between the surface/interfacial and interior layers. Our work advances the practical 32 integration and design of two-dimensional magnetic devices with tailored functionalities.
Peigen Li, Nanshu Liu, Jihai Zhang, Shenwei Chen, Xuhan Zhou, Donghui Guo, Cong Wang, Wei Ji, and Dingyong Zhong
Abstract:
Single-layer heterostructures of magnetic materials are unique platforms for studying spin-related phenomena in two dimensions (2D) and have promising applications in spintronics and magnonics. Here, we report the fabrication of 2D magnetic lateral heterostructures consisting of single-layer chromium triiodide (CrI3) and chromium diiodide (CrI2). By carefully adjusting the abundance of iodine based on molecular beam epitaxy, single-layer CrI3–CrI2 heterostructures were grown on Au(111) surfaces with nearly atomic-level seamless boundaries. Two distinct types of interfaces, i.e., zigzag and armchair interfaces, have been identified by means of scanning tunneling microscopy. Our scanning tunneling spectroscopy study combined with density functional theory calculations indicates the existence of spin-polarized ground states below and above the Fermi energy localized at the boundary. Both the armchair and zigzag interfaces exhibit semiconducting nanowire behaviors with different spatial distributions of density of states. Our work presents a novel low-dimensional magnetic system for studying spin-related physics with reduced dimensions and designing advanced spintronic devices.
Two-dimensional magnetic semiconductors provide a platform for studying physical phenomena at atomically thin limit, and promise magneto-optoelectronic devices application. Here, we report light helicity detectors based on graphene-CrI3-graphene vdW heterostructures. We investigate the circularly polarized light excited current and reflective magnetic circular dichroism (RMCD) under various magnetic fields in both monolayer and multilayer CrI3 devices. The devices exhibit clear helicity-selective photoresponse behavior determined by the magnetic state of CrI3. We also find abnormal negative photocurrents at higher bias in both monolayer and multilayer CrI3. A possible explanation is proposed for this phenomenon. Our work reveals the interplay between magnetic and optoelectronic properties in CrI3 and paves the way to developing spin-optoelectronic devices.
