arXiv subjects

Peter Finkel

Publications and source records attributed to Peter Finkel.

5 recordsLinked to original sources

arXiv2026

Magnetoelectric Wireless Power Transfer Receivers for Sub-Millimeter Scale Implantable Bioelectronics

Implanted biomedical devices for continuous physiological monitoring require reliable wireless power delivery to anatomically constrained and sensitive sites where batteries are impractical or hazardous. Existing wireless power transfer (WPT) modalities, including inductive coils and ultrasonic transducers suffer from performance degradation as receiver dimensions are miniaturized, limiting their application for space-limited locations such as fingertips, the ocular cavity, and intracranial sites. We present a microelectromechanical systems (MEMS) magnetoelectric WPT receiver integrating piezoelectric aluminum scandium nitride and magnetostrictive iron-cobalt/silver multilayer thin-films, microfabricated within a footprint of 770 x 360 x 2.25 micrometers. The receiver operates at its 100 kHz flexural-mode resonance with a quality factor of 1180 and delivers 1.0 microwatt to a matched 10 kohm load under a standard-compliant 205 micro-Tesla RMS excitation field. This device exhibits a magnetoelectric coefficient of 1274 V cm-1 Oe-1 and a power figure of merit (FOMP) of 4.05 x 10-3 mW cm-3 Oe-2 Hz-1, both the highest reported values of comparable magnetoelectric WPT receivers. The FOM is 20-fold higher than the next best comparable-frequency device. These miniaturized devices establish MEMS magnetoelectric transduction as a scalable platform for battery-free wireless powering of microwatt-class implants in the most anatomically demanding regions of the body.

physics.app-ph↗

arXiv2018

Ultra-low-field magneto-elastocaloric cooling in a multiferroic composite device

The advent of caloric materials for magnetocaloric, elastocaloric, and electrocaloric cooling is changing the landscape of solid state cooling technologies with potentials for high-efficiency and environmentally-friendly residential and commercial cooling as well as heating applications. Given that caloric materials are ferroic materials which undergo first (or second) order transitions near room temperature, they open up intriguing possibilities for novel multiferroic devices with hitherto unexplored functionalities coupling their thermal properties with different fields (magnetic, electric, and stress) through composite configurations. Here, we demonstrate a composite magneto-elastocaloric effect with ultra-low magnetic field (0.16 T) in a compact geometry to generate a cooling temperature change as large as 4 K using a magnetostriction/superelastic alloy composite. Such composite systems can be used to circumvent shortcomings of existing technologies such as the need for high-stress actuation mechanism for elastocaloric materials and the high magnetic-field requirement of magnetocaloric materials, while enabling new applications such as compact remote cooling devices.

cond-mat.mtrl-sci↗

arXiv2017

Effect of aging and Mn substitution on anisotropy of third generation piezoelectrics

We predict a new candidate high-temperature high-pressure structure of FeSiO$_3$ with space-group symmetry Cmmm by applying an evolutionary algorithm within DFT+U that we call post-perovskite II (PPv-II). An exhaustive search found no other competitive candidate structures with ABO$_3$ composition. We compared the X-ray diffraction (XRD) pattern of FeSiO$_3$ PPv-II with experimental results of the recently reported "H-phase" of (Fe,Mg)SiO$_3$. The intensities and positions of two main X-ray diffraction peaks of PPv-II FeSiO$_3$ compare well with those of the H-phase. We also calculated the static equation of state, the enthalpy and the bulk modulus of the PPv-II phase and compared it with those of perovskite (Pv) and post-perovskite (PPv) phases of FeSiO$_3$. According to the static DFT+U computations the PPv-II phase of FeSiO$_3$ is less stable than Pv and PPv phases under lower mantle pressure conditions at T=0 K and has a higher volume. PPv-II may be entropically stabilized, and may be a stable phase in Earth's lower mantle, coexisting with {α-PbO$_2$ (Columbite-structure) silica and perovskite, or with magnesiowustite and/or ferropericlase, depending on bulk composition.

cond-mat.mtrl-sci↗

arXiv2016

Strain-assisted magnetization reversal in Co/Ni multilayers with perpendicular magnetic anisotropy

Multifunctional materials composed of ultrathin magnetic films with perpendicular magnetic anisotropy combined with ferroelectric substrates represent a new approach toward low power, fast, high density spintronics. Here we demonstrate Co/Ni multilayered films with tunable saturation magnetization and perpendicular anisotropy grown directly on ferroelectric PZT [Pb(Zr_xTi_1-x)O_3] substrate plates. Electric fields up to +/- 2 MV/m expand the PZT by 0.1% and generate at least 0.02% in-plane compression in the Co/Ni multilayered film. Modifying the strain with a voltage can reduce the coercive field by over 30%. We also demonstrate that alternating in-plane tensile and compressive strains (less than 0.01%) can be used to propagate magnetic domain walls. This ability to manipulate high anisotropy magnetic thin films could prove useful for lowering the switching energy for magnetic elements in future voltage-controlled spintronic devices.

cond-mat.mes-hall↗

arXiv2013

Arrhenius-type domain growth in Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals

Single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) poled along [001] were investigated by dielectric, x-ray, and polarized light (PLM) and piezo-force microscopy (PFM) methods. PLM revealed {100} macro-domain plates that formed after poling, whose size increased on heating between room temperature and a rhombohedral \rightarrow tetragonal phase transition, above which point a break-up of the macro-domain plates was observed. Corresponding PFM studies demonstrated that poling reduced the size of stripe-like domains that were internal to the macro-domain plates, whose size also increased on heating to TR-T. The temperature dependence of both the size of the macro-domain plates and internal sub-domains followed the Arrhenius relation with the activation energy of 0.4-0.5eV. The coercive field displays an abnormal increase on heating below TR-T, different than that for PMN-PT. The anomalously increased coercive field can be ascribed to the Arrhenius-type domain growth, indicating a simple thermally activated process and an important role of hierarchial domains in the improved performance of PIN-PMN-PT.

cond-mat.mtrl-sci↗