Designing Magnetism in High Entropy Oxides

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Spin and exchange disorder in magnetic systems influence quantum criticality, frustration, and spin dynamics.
• Broad tunability and understanding of strong disorder effects remain limited.
• High entropy materials offer a unique platform for exploring disorder-driven phenomena.

Purpose of the Study:

• To explore high entropy oxides as a route to designing materials with tunable magnetic behaviors.
• To investigate the role of strong local compositional disorder in generating diverse magnetic responses.
• To understand and control magnetic uniformity and dynamics in disordered systems.

Main Methods:

• Synthesis of single-crystal La(Cr$_{0.2}$ Mn$_{0.2}$ Fe$_{0.2}$ Co$_{0.2}$ Ni$_{0.2}$ )O$_{3}$ films as a model system.
• Utilizing a classical Heisenberg model to describe magnetic interactions in disordered systems.
• Synthesizing model-predicted materials to validate theoretical predictions.

Main Results:

• Demonstrated that high entropy oxides can exhibit tunable magnetic behaviors, from ordered states to dynamic spin interactions.
• Showcased how compositional disorder can paradoxically lead to magnetic uniformity.
• Identified an incipient quantum critical point in materials with competing magnetic ordering types.
• Achieved controllable exchange bias behaviors, comparable to bilayer heterojunctions.

Conclusions:

• High entropy oxides provide a versatile platform for engineering magnetic properties through controlled disorder.
• The study offers a path toward continuous control over magnetic ordering types and critical temperatures.
• This approach enables the development of materials with tunable magnetic behaviors and novel functionalities like exchange bias.