Ferroelectronics Lab

This past week, Steve gave a contributed talk on theoretical calculations of strain dependent spin orbit splitting in PtMn₃ and its effect on intrinsic transport properties.

Abstract: Efficient charge-to-spin current conversion in materials is crucial to the development of spintronic memory or logic devices. A promising and established method of spin current generation is the injection of charge current through a crystal with a strong intrinsic spin Hall conductivity. Recently, a class of antiferromagnets with the composition XMn₃, where X={Pt, Ir, Rh}, have been identified as materials with large intrinsic spin Hall conductivities stemming from their non-trivial spin order. The exact role of antiferromagnetic spin texture on the generated spin current, however, is not fully understood. Temperature-dependent triangular AFM – collinear AFM phase transitions in chemically ordered PtMn₃ can be exploited to probe this directly. Here, we report on the growth and magneto-transport measurement of ordered PtMn3 thin films. Harmonic transport measurement techniques utilizing spin-transfer torques were performed to determine the spin and anomalous Hall conductivities at select temperatures.

Some of Peter’s artwork submitted to the annual calendar competition was chosen to hang in the hallway of the HH Dow building, home of the UM MSE department. If you are walking through, check it out!

Peter gave an invited talk at the recent college of engineering graduate student coffee hour on the novel and distortion dependent magnetic properties of entropy-stabilized oxides. Every two weeks, the graduate student council gives two graduate students the opportunity to give talks at this cross-department meeting.

Peter and other members of the UM MSE graduate student council organized and ran an outreach event at local Forsythe Middle School. There, volunteers taught a class on metallurgy and materials science, demo-ing metal casting and using our portable SEM to look at material microstructures. They presented to over 200 students over the course of 2 days, who had a great time learning about materials science
This event was sponsored in part by Joyworks Studio, who donated the pewter for casting and allowed us to give students a part to take home that they cast themselves.

Peter chaired the ferroelectrics session and gave a contributed talk at the 2018 Conference on Electronic and Advanced Materials this January, in Orlando, FL. His talk was about our recent work on entropy stabilized oxides and disorder dependent effects on magnetic structure. The abstract is provided below, and a big thanks to the American Ceramic Society.

Abstract: Entropy-stabilized materials are stabilized by the configurational entropy of the constituents, rather than the enthalpy of formation of the compound. A unique benefit to entropic stabilization is the increased solubility of elements, which opens a broad compositional space with subsequent local chemical and structural disorder resulting from different atomic sizes and preferred coordinations of the constituents. As the magnetic and electronic properties of oxides are strongly correlated to their chemistry and electronic structure, entropy stabilization could lead to interesting and novel properties. Anisotropic magnetic exchange and the presence of a critical blocking temperature indicates that the entropy-stabilized oxides considered here are antiferromagnetic. Changing the composition of the oxide tunes the disorder and exchange bias and here we exploit this tunability to enhance the strength of the exchange field by a factor of 10x at low temperatures, when compared to a CoO heterostructure. Significant deviations from the rule of mixtures are observed in the structural and magnetic parameters, indicating that the crystal is dominated by configurational entropy. Our results reveal that the unique characteristics of entropy stabilized materials can be utilized to engineer magnetic functional phenomena in oxide thin films.