We report large (>10%) magnetization modulation by ferroelectric polarization reversal in the ferroelectric-ferromagnetic BaTiO3/La0.67Sr0.33MnO3 (BTO/LSMO) heterostructures. We find that the electrically induced change in magnetization is limited to the BTO/LSMO interface but extends about 3 nm deep into the LSMO layer—far beyond the expected screening length of metallic LSMO. It is suggested that this effect is due to a metal-insulator transition occurring at the BTO/LSMO interface as a result of electrostatic doping.
1 September 2019 in Journal of Magnetism and Magnetic Materials
We demonstrate that Fe2TeO6 is a magnetoelectric antiferromagnet with voltage-controllable boundary magnetization. This provides experimental evidence of the theoretical prediction that boundary magnetization is a universal property of magnetoelectric antiferromagnets including boundary magnetization at a surface orthogonal to the polar direction. Highly (110) textured Fe2TeO6 thin films were grown by pulsed laser deposition, terminating in Te-O at the (110) surface due to a surface reconstruction. Magnetic dc susceptibility measurements of both Fe2TeO6 powder and thin film samples confirm antiferromagnetic long-range order. Finally, measurements of x-ray magnetic circular dichroism combined with photoemission electron microscopy (XMCD-PEEM) provide a lower bound to the spin and angular magnetic moment of the surface Fe ions.
31 January 2017 in Journal of Physics: Condensed Matter
From the Cr 2p 3/2 x-ray magnetic circular dichroism signal, there is clear evidence of interface polarization with overlayers of both Pd and Pt on chromia (Cr 2 O 3 ). The residual boundary polarization of chomia is stronger for a Pt overlayer than in the case of a Pd overlayer. The reduction of chromia boundary magnetization with a paramagnetic metal overlayer, compared to the free surface, is interpreted as a response to the induced spin polarization in Pt and Pd. Magnetization induced in a Pt overlayer, via proximity to the chromia boundary magnetization, is evident in the polar magneto-optical Kerr measurements. These results are essential to explainations why Pt and Pd are excellent spacer layers for voltage controlled exchange bias, in the [Pd/Co] n /Pd/Cr 2 O 3 and [Pt/Co] n /Pt/Cr 2 O 3 perpendicular magneto-electric exchange bias systems. The findings pave the way to realize ultra-fast reversal of induced magnetization in a free moment paramagnetic layer, with possible application in voltage-controlled magnetic random access memory.
The frequency dependence of the electric-field-induced magneto-optical Faraday effect is investigated in the magnetoelectric antiferromagnet chromia. Two electrically induced Faraday signals superimpose in proportion to the linear magnetoelectric susceptibility and the antiferromagnetic order parameter . The relative strength of these contributions is determined by the frequency of the probing light and can be tuned between extreme characteristics following the temperature dependence of or . The frequency dependence is analyzed in terms of electric dipole transitions of perturbed crystal-field states. The results allow us to measure voltage-controlled selection, isothermal switching, and temperature dependence of in a tabletop setup. The voltage-specific Faraday rotation is independent of the sample thickness, making the method scalable and versatile down to the limit of dielectric breakdown.
Controlling infrared thermal radiations can significantly improve the environmental adaptability of targets and has attracted increasing attention in the field of thermal camouflage. Thermal emitters based on Ge2Sb2Te5 (GST) can flexibly change their radiation energy by controlling the reversible phase transition of GST, which possesses fast switching speed and low power consumption. However, the feasibility of the dynamic regulation of GST emitters lacks experimental and simulation verification. In this paper, we propose an electrically tunable thermal emitter consisting of a metal–insulator–metal plasmonic metasurface based on GST. Both optical and thermal simulations are conducted to optimize the structural parameters of the GST emitter. The results indicate that this emitter possesses large emissivity tunability, wide incident angle, polarization insensitivity, phase-transition feasibility, and dynamic thermal camouflage capability. Therefore, this work proposes a reliable optimization method to design viable GST-based thermal emitters. Moreover, it provides theoretical support for the practical application of phase-change materials in dynamic infrared thermal camouflage technology.