New magnetic materials for data storage and memory devices
doi:10.1038/nindia.2021.34 Published online 23 February 2021
Electron spins in atoms create an antiferromagnetic state by pointing themselves in the opposite direction. When such an antiparallel alignment fails, the electron spins collapse into a liquid-like state that is known as quantum spin liquid (QSL).
Laboratory experiments with specific magnetic materials have shown that an antiferromagnetic state and QSL can coexist, according to a team of physicists from the Saha Institute of Nuclear Physics (SINP) in Kolkata1.
Such a coexistence of two states creates strange patterns of electron spins that the researchers say could potentially be used to make data storage and memory devices.
The SINP team, teaming up with other physicists, doped specific metal-oxide-based polycrystalline materials with neodymium, a rare-earth element.
The researchers, led by Sangam Banerjee, then studied the resistivity, resistance, magnetisation and specific heat of the doped materials, with and without magnetic fields.
They found that the doping by neodymium converts the polycrystalline materials into a strong insulator at extremely low temperatures. Increasing the content of the doping element decreases the metal-insulator transition temperature.
The specific heat of the materials varies linearly with temperature in the insulating state and also with external magnetic fields, they report. This indicates that the materials display fluctuations of electron spins even at the lowest temperatures, with and without magnetic fields.
This, in turn, creates strange electron spin patterns. Such a property could be utilised for topological quantum computation, Banerjee says.
1. Mondal, S. et al. Role of f − d exchange interaction and Kondo scattering in the Nd-doped pyrochlore iridate (Eu1−xNdx) 2Ir2O7. Phys. Rev. B. 102, 155139 (2020)