Electrical heating lets a small field reverse a cold layered magnet
Brief electrical heating allowed a weak magnetic field to select the orientation of a nickel-containing layered crystal as it cooled. Electrical and optical measurements tracked repeated reversals. The peer-reviewed experiment demonstrates control of a magnetic state under cryogenic conditions, with a transition temperature far below room temperature; it is an experimental material result rather than a commercial memory device.
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Heating enables reversal under a small magnetic field
A peer-reviewed laboratory experiment reversed the magnetic orientation of a layered nickel-containing crystal with heat generated electrically. The work involved Lawrence Berkeley National Laboratory and researchers at the University of California, Berkeley. They studied Ni1/4TaSe2, a material with nickel between tantalum diselenide layers. Heating temporarily removed its magnetic order; a small external field then selected the direction restored during cooling.[1]
Optical images support the electrical reading
An external field of about 2 mT was sufficient during cooling, around 100 times below the measured coercive field, the field associated with resistance to reversal. Changing the external field’s sign repeatedly selected opposite magnetic states. Electrical measurements tracked the transitions, while optical imaging independently showed the same reversal. Agreement between them supported a magnetic origin for the electrical change rather than an unrelated signal.[1]
The demonstration operates far below room temperature
Most measurements began at 2 K. The crystal’s Curie temperature, where its magnetic order disappears, is around 55 K. Higher starting temperatures reduced the current needed for switching, consistent with heat assisting the change. Here, memory refers to the possibility of electrically changing and reading the magnetic state. It did not establish room-temperature operation, a commercial memory array or the energy efficiency of a complete device.[1]
