Magnetostructural phase transition assisted by temperature in Ag-αMnO2: a density functional theory study

Area of Science:

• Materials Science
• Solid State Physics
• Computational Chemistry

Background:

• Silver-alpha-manganese dioxide (Ag-αMnO2) is a crystalline material featuring parallel silver atom chains within hollandite manganese dioxide tunnels.
• Understanding its structural and magnetic properties is crucial for potential applications.

Purpose of the Study:

• To investigate the structural and magnetic phases of Ag-αMnO2 using first-principles calculations.
• To determine the stability of different Ag-αMnO2 configurations and predict phase transition temperatures.

Main Methods:

• First-principles total energy calculations were employed.
• Phonon dispersion analysis was used to assess structural stability.
• Magnetic ordering and structural configurations were analyzed at different temperatures.

Main Results:

• Two stable magnetic phases were identified: an antiferromagnetic phase (I4/m) with linear silver chains at 0 K and a non-magnetic phase (P21/c) with zigzag silver chains at higher temperatures.
• The non-magnetic state with linear silver chains was found to be unstable.
• A magnetostructural phase transition temperature (Tc) of approximately 125 K was predicted between the two stable phases.

Conclusions:

• Ag-αMnO2 exhibits distinct stable magnetic and structural phases.
• The predicted phase transition at ~125 K is a key characteristic of this material.
• These findings provide fundamental insights into the behavior of Ag-αMnO2