Abstract
The significant inversion symmetry breaking specific to wurtzite semiconductors, and the associated spontaneous electrical polarization, lead to outstanding features such as high density of carriers at the GaN/(Al,Ga)N interface—exploited in high-power/high-frequency electronics—and piezoelectric capabilities serving for nanodrives, sensors and energy harvesting devices. Here we show that the multifunctionality of nitride semiconductors encompasses also a magnetoelectric effect allowing to control the magnetization by an electric field. We first demonstrate that doping of GaN by Mn results in a semi-insulating material apt to sustain electric fields as high as 5 MV cm−1. Having such a material we find experimentally that the inverse piezoelectric effect controls the magnitude of the single-ion magnetic anisotropy specific to Mn3+ ions in GaN. The corresponding changes in the magnetization can be quantitatively described by a theory developed here.
Highlights
The significant inversion symmetry breaking specific to wurtzite semiconductors, and the associated spontaneous electrical polarization, lead to outstanding features such as high density of carriers at the GaN/(Al,Ga)N interface—exploited in high-power/high-frequency electronics—and piezoelectric capabilities serving for nanodrives, sensors and energy harvesting devices
Correspondence and requests for materials should be addressed to T.D. It has been known for a long time that piezoelectricity specific to crystals with no inversion symmetry offers a spectrum of outstanding functional properties
A number of physical mechanisms has been invoked in order to explain magnetoelectric effects in various magnetic systems[15,16]
Summary
The significant inversion symmetry breaking specific to wurtzite semiconductors, and the associated spontaneous electrical polarization, lead to outstanding features such as high density of carriers at the GaN/(Al,Ga)N interface—exploited in high-power/high-frequency electronics—and piezoelectric capabilities serving for nanodrives, sensors and energy harvesting devices. We first demonstrate that doping of GaN by Mn results in a semi-insulating material apt to sustain electric fields as high as 5 MVcm À 1 Having such a material we find experimentally that the inverse piezoelectric effect controls the magnitude of the single-ion magnetic anisotropy specific to Mn3 þ ions in GaN. Because of Anderson-Mott and Hubbard-Mott localization of carriers residing in the Mn impurity band, the semi-insulating character of Ga1 À xMnxN persists up to the highest available Mn concentrations In this dilute magnetic insulator, the exchange coupling between Mn3 þ ions is dominated by short-range ferromagnetic superexchange interactions leading to a ferromagnetic ordering at TCt1 K for xt3% The measurements are performed at TZ2 K and xt3%, that is in the paramagnetic regime Under these conditions, the inverse piezoelectric effect by stretching the elementary cell along the c axis affects the magnitude of the uniaxial magnetic anisotropy and, of the magnetization. Ga1 À xMnxN extend into the core of spintronic functionalities, like the manipulation of magnetization by the electric field
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