Voltage control of the long-range p-d exchange coupling in a ferromagnet-semiconductor quantum well hybrid structure

Abstract

Voltage control of ferromagnetism on the nanometer scale is highly appealing for the development of novel electronic devices. Here a key challenge is to implement and combine low power consumption, high operation speed, reliable reversibility and compatibility with semiconductor technology. Hybrid structures based on the assembly of ferromagnetic and semiconducting building blocks are attractive candidates in that respect as such systems bring together the properties of the isolated constituents: They are expected to show magnetic order as a ferromagnet and to be electrically tunable as a semiconductor. Here we demonstrate the electrical control of the exchange coupling in a hybrid consisting of a ferromagnetic Co layer and a semiconductor CdTe quantum well, separated by a thin non-magnetic (Cd,Mg)Te barrier. The effective magnetic field of the exchange interaction reaches up to 2.5 Tesla and can be turned on and off by application of 1 V bias across the heterostructure. The mechanism of this electric field control is essentially different from the conventional concept, in which wavefunctions are spatially redistributed to vary the exchange interaction, requiring high field strengths. Here we address instead control of the novel exchange mechanism that is mediated by elliptically polarized phonons emitted from the ferromagnet, i.e. the phononic ac Stark effect. An essential parameter of this coupling is the splitting between heavy and light hole states in the quantum well which can be varied by the electric field induced band bending. Thereby the splitting can be tuned with respect to the magnon-phonon resonance energy in the ferromagnet, leading to maximum coupling for flat band conditions. Our results demonstrate the feasibility of electrically controlled exchange coupling in hybrid semiconductor nanostructures at quite moderate electric field strengths.

25 pages, 5 figures, supplementary material

References in corpus (6)

• An effective magnetic field from optically driven phonons
• Integrating Magnetism into Semiconductor Electronics
• Long-range p-d exchange interaction in a ferromagnet-semiconductor hybrid structure
• Tunable spin polarization in III-V quantum wells with a ferromagnetic barrier
• Modulation of ferromagnetism in (In,Fe)As quantum wells via electrically controlled deformation of the electron wavefunctions
• Long-range p-d exchange interaction in a ferromagnet-semiconductor Co/CdMgTe/CdTe quantum well hybrid structure

Cited by in corpus (5)

• Half-Metal Spin-Gapless Semiconductor Junctions as a Route to the Ideal Diode
• Resonant Tunneling Anisotropic Magnetoresistance Induced by Magnetic Proximity
• Spin-spin interaction mediated by chiral phonons
• Rashba spin-orbit coupling enhanced magnetoresistance in junctions with one ferromagnet
• Optically induced spin electromotive force in ferromagnetic-semiconductor quantum well structure