Realization of semiconducting layered multiferroic heterojunctions via asymmetrical magnetoelectric coupling

Letter

Realization of semiconducting layered multiferroic heterojunctions via asymmetrical magnetoelectric coupling

Baishun Yang, Bin Shao, Jianfeng Wang, Yang Li, ChiYung Yam, Shengbai Zhang, and Bing Huang

Phys. Rev. B 103, L201405 – Published 21 May 2021

Abstract

Two-dimensional (2D) semiconducting multiferroics that can effectively couple magnetic and polarization $(P)$ orders have great interest for both fundamental research and technological applications in nanoscale, which are, however, rare in nature. In this paper, we propose a general mechanism to realize semiconducting 2D multiferroics via van der Waals (vdW) heterojunction engineering, as demonstrated in a typical heterostructure consisting of magnetic bilayer $Cr I_{3} (b i -Cr I_{3})$ and ferroelectric monolayer ${In}_{2} {Se}_{3}$ . Interestingly, the novel indirect orbital coupling between $Se 4 p$ and $Cr 3 d$ orbitals, intermediated by the interfacial $I 5 p$ orbitals, is switchable in the opposite $P$ configurations, resulting in an unexpected mechanism of strong asymmetrical magnetoelectric coupling. Therefore, along with the noticeable ferroelectric energy barrier induced by ${In}_{2} {Se}_{3}$ , the realization of opposite magnetic orders in opposite $P$ configurations can eventually result in the novel multiferroicity in $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ . Finally, we demonstrate that our mechanism can generally be applied to design other vdW multiferroics even with tunable layer thickness.

Received 7 September 2020
Revised 10 February 2021
Accepted 12 May 2021

DOI:https://doi.org/10.1103/PhysRevB.103.L201405

Physics Subject Headings (PhySH)

Magnetoelectric effect

Bilayer films Magnetic semiconductors Multiferroics

First-principles calculations

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Baishun Yang ^1,2, Bin Shao^1,2, Jianfeng Wang¹, Yang Li¹, ChiYung Yam ^1,2, Shengbai Zhang³, and Bing Huang^1,4,*

¹Beijing Computational Science Research Center, Beijing 100193, China
²Shenzhen JL Computational Science and Applied Research Institute, Shenzhen 518109, China
³Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
⁴Department of Physics, Beijing Normal University, Beijing 100875, China

^*bing.huang@csrc.ac.cn

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Issue

Vol. 103, Iss. 20 — 15 May 2021

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Images

Figure 1

Concept and schematic diagrams for realizing vdW multiferroics. (a) Electronic and magnetic states for a 2D bilayer magnet without (left panel) and with (right panel) an $E_{ef}$ . Arrows denote spin orders in $A B$ layers. (b) Ferroelectric double-well potential energy curve. $P ↑$ and $P ↓$ denote two opposite FE polarizations, while $E_{b}$ is the energy barrier between the $P ↑$ and $P ↓$ states. (c) Realization of vdW multiferroics via an asymmetrical ME coupling between the bilayer magnet and ML FE systems.
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Figure 2

Realization of vdW multiferroics in $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ . (a) Side views of $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ with $P ↑$ (left panel) and $P ↓$ (right panel). (b) Energy difference ( $Δ E$ ) between the FM and AFM states in the freestanding $b i − {CrI}_{3}$ and $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ , as a function of the fractional shift, which is obtained by sliding the top ${CrI}_{3}$ layer along the $b$ axis with respect to the bottom layer. $x = 0.0$ is the low-temperature (LT) phase, while $x = 1 / 3$ is the HT phase. The shaded area is where the FM- $P ↑$ and AFM- $P ↓$ states in Fig. 1 have been realized in $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ . (c) Switching path between the FM- $P ↑$ and AFM- $P ↓$ states for the HT-phase $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ . Blue and green circles are different magnetic states in the $P ↑$ and $P ↓$ configurations, respectively. When $P = 0$ , the system is nonferroelectric.
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Figure 3

Mechanism of multiferroicity in $b i − {CrI}_{3} / {In}_{2} {Se}_{3}$ where (a)–(c) are for $P ↑$ and (d)–(f) for $P ↓$ . (a), (d) Schematic diagrams of orbital coupling between interfacial I-1 and Se-1 $p$ orbitals as well as the virtual orbital hopping path between empty $Cr- 1 e_{g}$ and occupied $Cr- 2 t_{2 g}$ orbitals. Here, $Δ V$ is the relative energy difference between the two $t_{2 g}$ (and $e_{g}$ ) orbitals. In the lower part of the diagrams, $a_{1} (a_{2})$ and $e_{1} (e_{2})$ are the single- and doubly degenerate $p$ orbitals of I-1 (Se-1) atoms, respectively. (b), (e) Orbital-projected band structures (spin-up channel). (c), (f) PDOS.
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Figure 4

Realization of vdW multiferroics in $t r i − {CrI}_{3} / {In}_{2} {Se}_{3}$ . Switching path of the HT-phase $t r i − {CrI}_{3} / {In}_{2} {Se}_{3}$ . Blue and green circles represent different magnetic states in the $P ↑$ and $P ↓$ configurations, respectively. $P = 0$ is the nonpolarized configuration.
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