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Fingerprints of Universal Spin-Stiffness Jump in Two-Dimensional Ferromagnets
Roberto E Troncoso1, Arne Brataas1, Asle Sudbø1
1Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Physical Review Letters
|December 18, 2020
Summary
Researchers propose a new method to detect topological phase transitions in 2D magnetic materials using spin-transport experiments. This technique measures key properties of the Berezinskii-Kosterlitz-Thouless transition, offering a simpler experimental route.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Recent advancements in synthesizing two-dimensional (2D) magnetic van der Waals systems.
- The Berezinskii-Kosterlitz-Thouless (BKT) phase transition is a key topological phenomenon in 2D systems.
- Experimental detection of the BKT transition in 2D magnets has been challenging.
Purpose of the Study:
- To propose a novel experimental setup for detecting the topological BKT phase transition in 2D magnetic van der Waals systems.
- To provide a method for measuring universal critical phenomena in low-dimensional magnetic systems.
- To facilitate experimental investigations beyond the standard Ginzburg-Landau theory.
Main Methods:
- Utilizing spin-transport experiments on 2D magnetic van der Waals structures.
- Analyzing spatial correlations of injected spin currents into metallic leads.
- Measuring the universal jump in ferromagnet spin stiffness (2/π) and its temperature dependence.
Main Results:
- Demonstrated that spatial spin current correlations can quantify the BKT transition.
- Showcased the ability to measure the predicted universal jump in spin stiffness.
- Confirmed the predicted square root dependence of spin stiffness on temperature approaching the transition.
Conclusions:
- The proposed setup offers a straightforward method for detecting the topological BKT phase transition in 2D magnetic systems.
- This work encourages experimental exploration of critical phenomena in low-dimensional magnetism.
- The findings pave the way for studying systems lacking a local order parameter.
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