Browsing by Subject "thin films"

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    Nonvolatile voltage controlled molecular spin state switching
    (AIP, 2019) Hao, G.; Mosey, A.; Jiang, X.; Yost, A. J.; Sapkota, K. R.; Wang, G. T.; Zhang, X.; Zhang, J.; N’Diaye, A. T.; Cheng, R.; Xu, X.; Dowben, P. A.; Physics, School of Science
    Voltage-controlled room temperature isothermal reversible spin crossover switching of [Fe{H2B(pz)2}2(bipy)] thin films is demonstrated. This isothermal switching is evident in thin film bilayer structures where the molecular spin crossover film is adjacent to a molecular ferroelectric. The adjacent molecular ferroelectric, either polyvinylidene fluoride hexafluoropropylene or croconic acid (C5H2O5), appears to lock the spin crossover [Fe{H2B(pz)2}2(bipy)] molecular complex largely in the low or high spin state depending on the direction of ferroelectric polarization. In both a planar two terminal diode structure and a transistor structure, the voltage controlled isothermal reversible spin crossover switching of [Fe{H2B(pz)2}2(bipy)] is accompanied by a resistance change and is seen to be nonvolatile, i.e., retained in the absence of an applied electric field. The result appears general, as the voltage controlled nonvolatile switching can be made to work with two different molecular ferroelectrics: croconic acid and polyvinylidene fluoride hexafluoropropylene.
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    Study of the Long-Range Exchange Coupling in Nd-Fe-B/Ti/Fe Multilayered Structure
    (MDPI, 2024-02) Yazdani, Saeed; Phillips, Jared; Mosey, Aaron; Bsaibes, Thomas; Decca, Ricardo; Cheng, Ruihua; Physics, School of Science
    The exchange coupling between two ferromagnetic thin films, one with magnetically hard and the other with soft phases, separated by a thin non-magnetic layer, is studied. Nd-Fe-B/Ti/Fe thin film heterostructures were fabricated using DC magnetron sputtering on Si substrates, which were heated in situ at 650 °C using a house-built vacuum-compatible heater. The effect of the thickness of the Ti buffer layer and the annealing temperature on the formation of various phases of Nd-Fe-B was investigated. The effect of the thickness of the non-magnetic Ti spacer layer on the exchange coupling strength between the hard phase Nd-Fe-B ferromagnetic thin layer and the soft phase transition metal Fe layer was experimentally investigated. Hysteresis loops of multilayer thin films indicate an antiferromagnetic coupling was observed when the thickness of the spacer layer was 2 nm. This is within the range of an antiferromagnetic coupling calculation based on RKKY theory predictions.