Kavli Affiliate: Scott K. Cushing
| First 5 Authors: Kim H. Pham, Kiarash Gordiz, Jonathan M. Michelsen, Hanzhe Liu, Daniele Vivona
| Summary:
Ionic conduction in solids that exceeds 0.01 S/cm is predicted to involve
collective phonon-ion interactions in the crystal lattice. Here, we use theory
and experiment to measure the contribution of possible collective phonon-ion
modes to Li+ migration in Li0.5La0.5TiO3. The ab initio calculations reveal
that only a few phonon modes, mostly TiO6 rocking modes below 6 Terahertz,
provide over 40% of the energy required for the Li+ hop in Li0.5La0.5TiO3.
Laser-driving the TiO6 rocking modes decreases the measured impedance ten-fold
compared to exciting acoustic and optical phonons at similar energy densities.
The decreased impedance persists on thermalization timescales. These findings
provide new insights on phonon-coupled ion migration mechanisms, material
design rules, and the potential for metastable states for opto-ionic materials.
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