Nonreciprocal second harmonic generation in a magnetoelectric material

Abstract

Mirror symmetries are of particular importance because they are connected to fundamental properties and conservation laws. Spatial inversion and time reversal are typically associated to charge and spin phenomena, respectively. When both are broken, magnetoelectric cross-coupling can arise. In the optical regime, a difference between forward and backward propagation of light may result. Usually, this nonreciprocal response is small. We show that a giant nonreciprocal optical response can occur when transferring from linear to nonlinear optics, specifically second harmonic generation (SHG). CuB2O4 exhibits SHG transmission changes by almost 100% upon reversal of a magnetic field of just ±10 mT. The observed nonreciprocity results from an interference between magnetic-dipole and electric-dipole SHG. Although the former is inherently weaker than the latter, a resonantly enhanced magnetic-dipole transition has a comparable amplitude as a nonresonant electric-dipole transition, thus maximizing the nonreciprocity. Multiferroics and magnetoelectrics are an obvious materials platform to exhibit nonreciprocal nonlinear optical functionalities.

Co‐Polarized Second Harmonic Generation Induced by Ferroelectric Domains and Domain Wall Arrays

“…[4,6] In multiferroic materials, these breaking types are simultaneously contained. The seminal work [15] on the discovery of magnetoelectric coupling effects through SHG in multiferroic YMnO 3 has ignited a series of interesting investigations on ferroelectricity, [6,[16][17][18][19][20][21][22][23] antiferromagnetism, [24][25][26][27][28][29] and magnetoelectric domain dynamics. [30] As a typical example of breaking state at boundaries, domain wall (DW) has been recently demonstrated to possess diverse and intriguing properties that differ from those of the domain entities.…”

“…[ 4,6 ] In multiferroic materials, these breaking types are simultaneously contained. The seminal work [ 15 ] on the discovery of magnetoelectric coupling effects through SHG in multiferroic YMnO 3 has ignited a series of interesting investigations on ferroelectricity, [ 6,16–23 ] antiferromagnetism, [ 24–29 ] and magnetoelectric domain dynamics. [ 30 ]…”

Magnetoelectric dissociation of Alzheimer’s β-amyloid aggregates

“…Magnetoelectric materials exhibit rigidly coupled magnetic and electric polarization ( 1 , 2 ), which is the basis for their unique optical ( 3 ), mechanical ( 4 ), and thermal properties ( 5 ). According to the origin of magnetoelectric coupling, two different types of magnetoelectric materials exist: (i) single-phase multiferroic oxides with spin-orbit interactions and (ii) heterogeneous multiphase oxides with individual magnetostrictive and piezoelectric composites linked via interfaces ( 6 ).…”

Demonstration of a Plasmonic Nonlinear Pseudodiode

“…Such asymmetric behavior is sometimes referred to as “ nonreciprocal SHG ”, both in the metasurface , and solid-state physics , communities. We share the view that such a nomenclature is improper in the case of SHG, since the concept of nonrecipocity is not well-defined for nonlinear optics. ,, For any N -port system, the Lorentz reciprocity implies the symmetry of the scattering matrix boldS̅̅ normalT = S̅̅ , where T denotes the transpose operator.…”

“…Thus, higher linear absorption upon backward excitation (see Figure S5 and discussion above) results in a higher probability of two-photon absorption and subsequent NPL, which is consistent with our observations. Such asymmetric behavior is sometimes referred to as "nonreciprocal SHG", both in the metasurface 13,44 and solidstate physics 71,72 communities. We share the view that such a nomenclature is improper in the case of SHG, since the concept of nonrecipocity is not well-defined for nonlinear optics.…”