Virginia Commonwealth University

Jayasimha Atulasimha

Supriyo Bandyopadhyay

Md Mamun Al-Rashid

Dhritiman Bhattcaharya

Ayan Kumar Biswas

Vishnu-Baba Sundaresan

Joshua Clarke

A fixed magnetic skyrmion in a memory or Boolean logic or non-Boolean computing element is reversibly switched or switchable (1) with only an electric field and without a magnetic field or spin current; and (2) using voltage control of magnetic anisotropy (VCMA) to reduce the spin current needed to switch the skyrmion. Some embodiments switch between four states: two skyrmion states and two ferromagnetic states. Other embodiments switch between two states which are both skyrmionic, in which case the switching process may use ferromagnetic intermediate states, or both ferromagnetic, in which case the switching process may use skyrmionic intermediate states, or between a Skyrmion and ferromagnetic state. Boolean and non-Boolean logic devices are also provided which are based on these switching methods.

Switching skyrmions with VCMA/electric field for memory, computing and information processing

Memory cells, non-volatile logic gates, and combinations thereof have magneto-tunneling junctions (MTJs) which are switched using potential differences across a piezoelectric layer in elastic contact with a magnetostrictive nanomagnet of an MTJ. One or more pairs of electrodes are arranged about the MTJ for supplying voltage across the piezoelectric layer for switching. A permanent magnetic field may be employed to change the positions of the stable magnetic orientations of the magnetostrictive nanomagnet. Exemplary memory cells and universal non-volatile logic gates show dramatically improved performance characteristics, particularly with respect to energy dissipation and error-resilience, over existing methods and architectures for switching MTJs such as spin transfer torque (STT) techniques.

Magneto-elastic non-volatile multiferroic logic and memory with ultralow energy dissipation

A magnetostrictive-piezoelectric multiferroic single- or multi-domain nanomagnet whose magnetization can be rotated through application of an electric field across the piezoelectric layer has a structure that can include either a shape-anisotropic mangnetostrictive nanomagnet with no magnetocrystalline anisotropy or a circular nanomagnet with biaxial magnetocrystalline anisotropy with dimensions of nominal diameter and thickness. This structure can be used to write and store binary bits encoded in the magnetization orientation, thereby functioning as a memory element, or perform both Boolean and non-Boolean computation, or be integrated with existing magnetic tunneling junction (MTJ) technology to perform a read operation by adding a barrier layer for the MTJ having a high coercivity to serve as the hard magnetic layer of the MTJ, and electrical contact layers of a soft material with small Young's modulus. Equivalently, mangnetostrictive nanomagnetic elements whose magnetization is rotated by strain transferred from the substrate that has acoustic waves propagating on the substrate can be used.

Planar multiferroic/magnetostrictive nanostructures as memory elements, two-stage logic gates and four-state logic elements for information processing

A magnetoelectric element of a surgical tool positioned in the body of a subject is controllably bent or elongated under the influence of an applied magnetic field. A piezoelectric layer in the magnetoelectric element provides output that can be used to determine the actual amount of bending or elongation of the magnetoelectric element, and this actual amount is compared to a theoretical amount of bending or elongation which would result from the applied magnetic field. Any differences between the actual and theoretical amounts provide feedback to the surgeon for performing the surgical procedure. Preferably, tactile feedback is provided to the surgeon.

Growing community of inventors

Glen Allen, VA, United States of America

Jayasimha Atulasimha