Voltage controlled Néel vector rotation in zero magnetic field

Abstract

Multi-functional thin films of boron (B) doped Cr2O3 exhibit voltage-controlled and nonvolatile Néel vector reorientation in the absence of an applied magnetic field, H. Toggling of antiferromagnetic states is demonstrated in prototype device structures at CMOS compatible temperatures between 300 and 400 K. The boundary magnetization associated with the Néel vector orientation serves as state variable which is read via magnetoresistive detection in a Pt Hall bar adjacent to the B:Cr2O3 film. Switching of the Hall voltage between zero and non-zero values implies Néel vector rotation by 90 degrees. Combined magnetometry, spin resolved inverse photoemission, electric transport and scanning probe microscopy measurements reveal B-dependent TN and resistivity enhancement, spin-canting, anisotropy reduction, dynamic polarization hysteresis and gate voltage dependent orientation of boundary magnetization. The combined effect enables H = 0, voltage controlled, nonvolatile Néel vector rotation at high-temperature. Theoretical modeling estimates switching speeds of about 100 ps making B:Cr2O3 a promising multifunctional single-phase material for energy efficient nonvolatile CMOS compatible memory applications.

Exchange Coupling in Synthetic Anion‐Engineered Chromia Heterostructures

“…Therefore, extensive efforts have been made to change magnetic ground state of Cr 2 O 3 via cation substitution to improve the EB field and to enhance T N . [ 16–19 ] Substitution in this manner not only introduces chemical strain which influences the magnetic anisotropy and magnetoelastic coupling but may also change the valence state of chromium by creating oxygen vacancies leading to effective spin state transitions. Recently, oxides with mixed‐anions become experimentally achievable and the influence of the anion on the physical properties is an emerging research field.…”

Antiferromagnetic Ordering and Uncoupled Spins in CaFe2O4 Thin Films Probed by Spin Hall Magnetoresistance

“…The use of antiferromagnetic (AF) materials as active elements in devices is increasingly attracting interest, as it offers the possibility for complex functionalities. [ 1 ] This is made possible by the availability of a wide variety of different AF structures arising from the interplay of exchange interactions between spins with multiple strengths ( J ). In addition, antiferromagnets can display strong magnetoelastic coupling, insulating behavior, zero stray fields and THz dynamics, which all make them promising candidates for the next generations of spin‐based technologies.…”

Magnetoelectric Switching Energy of Antiferromagnetic Cr2O3 Used for Spintronic Logic Devices and Memory

“…[ 11 ] In particular, after the report of Néel temperature enhancement to ≈400 K using boron doping [ 12,13 ] and ME switching of Cr 2 O 3 thin‐film systems, [ 14,15 ] Cr 2 O 3 and its perpendicular exchange‐coupling heterostructures have been widely studied, [ 16–31 ] and recently a writing speed of ≈100 ps for spintronic memory application is theoretically expected. [ 32 ] Furthermore, the application of this ME material in spintronic logic devices has also been reported. [ 33 ] Simultaneously, some new phenomena for Cr 2 O 3 have been independently conveyed, [ 34–39 ] indicating that this spintronic material has great potential for fundamental research and practical applications.…”