Electrically controlled surface magnetism

Thursday, 27 April 2017 - 3:30pm
Peter Dowben, University of Nebraska-Lincoln
Refreshments at 3:00 pm in the Physics Conference Room LD 154B

Manipulation of magnetically ordered states by electrical means is among the most promising approaches towards novel spintronic devices [1-4]. Indeed, voltage control of magnetism is a “holy grail” of spintronics. Electric control of the exchange bias can be realized when the passive antiferromagnetic pinning layer, in an exchange bias system, is replaced by a magneto-electric antiferromagnet [3]. In a magneto-electric material, an applied electric field induces a net magnetic moment. Surprisingly this net magnetic moment, at the surface of a magneto-electric antiferromagnet, can be observed in spin-polarized photoemission [3], spin-polarized inverse photoemission [4], X-ray circular dichroism [4] and spin polarized low energy electron microscopy [5], when the antiferromagnetic single domain state is selected in a magneto-electric annealing process. In the single domain antiferromagnetic state of Cr2O3, a magnetic Cr2O3(0001) surface moment evolves which is robust against surface roughness. This has led to revived interest in the prototypical magneto-electric Cr2O3, where spontaneous ferroelectric order is absent, but a specific surface magnetic order enables electric control of a net spin polarization of the Cr2O3(0001) surface. Time permitting, some indication will be provided of the how magneto-electrics might be implemented into voltage controlled nonvolatile spintronic devices.

 

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