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Voltage controlled Néel vector rotation in zero magnetic field.
Ather Mahmood1, Will Echtenkamp1, Mike Street1
1Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA.
Nature Communications
|March 16, 2021
Summary
Boron-doped chromium oxide (Cr2O3) thin films enable voltage-controlled, nonvolatile switching of antiferromagnetic states without magnetic fields. This breakthrough offers potential for energy-efficient, high-temperature memory devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Antiferromagnetic materials offer potential for advanced memory technologies due to their fast dynamics and high density.
- Controlling antiferromagnetic order with electric fields, rather than magnetic fields, is crucial for low-power spintronic devices.
- Chromium oxide (Cr2O3) is an antiferromagnet with a Néel temperature (TN) above room temperature, making it suitable for practical applications.
Purpose of the Study:
- To investigate the voltage-controlled manipulation of antiferromagnetic states in boron-doped Cr2O3 (B:Cr2O3) thin films.
- To demonstrate nonvolatile Néel vector reorientation at high temperatures without an external magnetic field.
- To explore the potential of B:Cr2O3 as a multifunctional material for energy-efficient memory applications.
Main Methods:
- Fabrication of prototype device structures using B:Cr2O3 thin films.
- Utilized magnetoresistive detection in an adjacent platinum (Pt) Hall bar to read the magnetic state.
- Employed a combination of magnetometry, spin-resolved inverse photoemission spectroscopy, electric transport measurements, and scanning probe microscopy.
Main Results:
- Achieved voltage-controlled, nonvolatile Néel vector reorientation in B:Cr2O3 at temperatures between 300 and 400 K.
- Demonstrated switching of antiferromagnetic states via gate voltage, evidenced by changes in Hall voltage.
- Observed B-dependent enhancement of TN and resistivity, spin-canting, reduced anisotropy, and gate-voltage-dependent boundary magnetization.
Conclusions:
- B:Cr2O3 thin films exhibit promising multifunctional properties for advanced spintronic memory.
- The ability to control antiferromagnetic order with voltage at high temperatures is a significant step towards energy-efficient, nonvolatile memory.
- Theoretical modeling suggests switching speeds of approximately 100 ps, highlighting the material's potential for CMOS-compatible applications.
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