Papers by Keyword: Mixed Valence

Abstract: In contrast to the Moore’s Law exponential growth in CMOS transistor areal density, computer clock speeds have been frozen since 2003 due to excessive power dissipation. We present the development of a new digital switch, the PiezoElectronic Transistor (PET), designed to circumvent the speed and power limitations of the CMOS transistor. The PET operates on a novel principle: an electrical input is transduced into an acoustic pulse by a piezoelectric (PE) actuator, which, in turn, drives a continuous insulator-to-metal transition in a piezoresistive (PR) channel, thus switching on the device. Predictions of theory and simulation, assuming bulk materials properties can be approximately retained at scale, are that PETs can operate at one-tenth the present voltage of CMOS technology and 100 times less power, while running at multi-GHz clock speeds. CMOS-like computer architectures, such as a simulated adder, can be fully implemented. Materials development for PE and PR thin films approaching the properties of bulk single crystals, and a successful fabrication scheme, are the key to realizing this agenda. We describe progress in developing PE films (where d₃₃ is critical) and PR films (characterized by conductance and ON/OFF ratio) of demonstration quality. A macroscopic-scale PET has been built to demonstrate PET viability over large numbers of switching cycles. The perspective for the development of pressure-driven electronics will be outlined.

Abstract: The peculiarities of the Faraday rotation in the imperfect garnet-type crystals for which the lattice irregularities are represented by the mixed valence clusters of transition metal ions are analyzed. The model takes into account the cubic and low symmetry crystal fields acting on the metal ions and migration of the “extra” hole. The electric dipole transitions in these types of clusters with migrating hole coupled to the spin core through the double exchange mechanism are shown to lead to a significant magnetooptical activity in the visible range of spectrum. The intensity of these transitions can be comparable or higher than those for the magnetic dipole ones in the same range of frequencies.