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VOLTAGE CONTROLLED NON-VOLATILE SPIN STATE AND CONDUCTANCE SWITCHING OF A MOLECULAR THIN FILM HETEROSTRUCTURE

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thesis
posted on 06.04.2021, 13:21 by Aaron George MoseyAaron George Mosey
Thermal constraints and the quantum limit will soon put a boundary on the scale of new micro and nano magnetoelectronic devices. This necessitates a push into the limits of harnessable natural phenomena to facilitate a post-Moore’s era of design. Requirements for thermodynamic stability at room temperature, fast (Ghz) switching, and low energy cost narrow the list of candidates. Molecular electronic frontier orbital structure of some d-block transition metal ions in crystal fields will deform in response to their local energetic environment, giving rise to the eg and t2g suborbitals. More specifically, in an mononuclear Fe(II) complex, the energetic scale between these two orbitals yields an S=0 low spin diamagnetic state and an S=2 high spin paramagnetic state. Spin crossover complex [Fe{H2B (pz) 2 }2 (bipy)] will show locking of its spin state well above the transition temperature, with an accompanied change of conductivity, when placed in a polar environment. Here we show voltage controllable, room temperature, stable locking of the spin state, and the corresponding conductivity change, when molecular thin films of [Fe{H2B (pz) 2 }2 (bipy)] are deposited on a ferroelectric polyvinylidene fluoride hexafluropropylene substrate. This opens the door to the creation of a thermodynamically stable, room temperature, molecular multiferroic gated voltage device.

Funding

NSF-Chem 1565692

NSF-DMR 2003057

Advanced Light Source, Lawrence Berkeley National Labo- ratory, was supported by the U.S. Department of Energy (DOE) under contract no. DE-AC02-05CH11231

History

Degree Type

Doctor of Philosophy

Department

Physics and Astronomy

Campus location

Indianapolis

Advisor/Supervisor/Committee Chair

Ruihua Cheng

Additional Committee Member 2

Ricardo Decca

Additional Committee Member 3

Gabor Csathy

Additional Committee Member 4

Yogesh Joglekar

Additional Committee Member 5

Gautum Vermuri