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Large zero-field cooled exchange-bias in bulk Mn2PtGa
A K Nayak1, M Nicklas1, S Chadov1
1Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany.
Physical Review Letters
|August 29, 2014
Summary
We discovered a significant exchange-bias effect in the new Mn(2)PtGa compound. This effect, crucial for magnetic applications, arises from its unique ferrimagnetic ordering and low-temperature magnetic phases.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Heusler compounds are known for their diverse magnetic properties.
- Exchange bias is a critical phenomenon for spintronic devices.
- Understanding complex magnetic ordering is key to developing new magnetic materials.
Purpose of the Study:
- To investigate the magnetic properties of the novel tetragonal Heusler compound Mn(2)PtGa.
- To explore the origin of the observed exchange-bias effect.
- To characterize the low-temperature magnetic behavior and phase transitions.
Main Methods:
- First-principles calculations to determine electronic and magnetic structure.
- Magnetic measurements (e.g., magnetization vs. field, temperature dependence).
- Analysis of magnetic ordering, phase transitions, and disorder effects.
Main Results:
- Mn(2)PtGa exhibits ferrimagnetic ordering with ferromagnetic inclusions.
- A large exchange-bias effect is observed after zero-field cooling from the paramagnetic state.
- Complex low-temperature behavior includes field-induced irreversible transitions and a spin-glass-like phase.
- Ferrimagnetic ordering is essential for inducing exchange anisotropy during virgin magnetization.
Conclusions:
- The tetragonal Heusler compound Mn(2)PtGa displays significant exchange bias due to its specific magnetic ordering.
- The observed magnetic phenomena, including first-order transitions and spin-glass behavior, are linked to intrinsic material properties like antisite disorder.
- This research provides insights into the fundamental magnetic mechanisms in complex Heusler materials.
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