# Magnetization generation and giant nonlinear transport at symmetry-engineered interfaces

## TL;DR

Researchers engineered a new interface symmetry in a material system, enabling room-temperature effects like a giant nonlinear Hall effect and magnetization.

## Contribution

A new strategy to break in-plane mirror symmetries via crystallographic orientation engineering in heterostructures.

## Key findings

- A LaAlO3/SrTiO3 heterostructure with (112)-plane orientation breaks all in-plane mirror symmetries except one.
- The interface exhibits a giant nonlinear Hall effect and current-induced magnetization at room temperature.
- The nonlinear Hall effect magnitude is comparable to that of Weyl and Dirac systems.

## Abstract

Interfaces in heterostructures possess inherent inversion asymmetry and display diverse physical effects, however, the pristine in-plane mirror symmetries of the constituent layers are usually preserved at the interface. On-demand manipulation of these symmetries remains challenging. Here, we demonstrate a strategy to control the in-plane mirror symmetries of interfaces by engineering the crystallographic orientation of heterostructures. We design a workhorse system with a new orientation, i.e., the LaAlO3/SrTiO3 heterostructure with metallic interfaces in the (112)-plane. Such a high index orientation leads to the breaking of all the pristine mirror symmetries except the mirror plane perpendicular to the \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$[1\bar{1}0]$$\end{document}[11¯0] direction (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$${M}_{[1\bar{1}0]}$$\end{document}M[11¯0]), resulting in the Cs point symmetry with a metallic conduction. Consequently, this interface exhibits a giant nonlinear Hall effect characterized by a large Berry curvature dipole, a circular photogalvanic effect, and current-induced out-of-plane magnetization, all functional at room temperature. The magnitude of the nonlinear Hall effect rivals the Weyl and Dirac systems. Our work establishes a new strategy in exploring emerging electronic properties with nontrivial quantum geometry by designing the interface symmetry.

Symmetry breaking is key to numerous notable effects, for instance, the emergence of a Rashba interaction at interfaces between two materials. Here, Zhang, Ding, and coauthors succeed in breaking in-plane mirror symmetries via crystallographic engineering, and observe a giant non-linear Hall effect and current induced magnetization at room temperature.