Atomic-scale measurement of polar entropy

Debangshu Mukherjee, Sergei Prokhorenko, Leixin Miao, Ke Wang, Eric Bousquet, Venkatraman Gopalan, Nasim Alem

Research output: Contribution to journalArticle

Abstract

Entropy is a fundamental thermodynamic quantity that is a measure of the accessible microstates available to a system, with the stability of a system determined by the magnitude of the total entropy of the system. This is valid across truly mind boggling length scales, from nanoparticles to galaxies. However, quantitative measurements of entropy change using calorimetry are predominantly macroscopic, with direct atomic-scale measurements being exceedingly rare. Here, we experimentally quantify the polar configurational entropy (in meV/K) using sub-angstrom resolution aberration corrected scanning transmission electron microscopy in a single crystal of the prototypical ferroelectric LiNbO3 through the quantification of the niobium and oxygen atom column deviations from their paraelectric positions. Significant excursions of the niobium-oxygen polar displacement away from its symmetry-constrained direction are seen in single domain regions which increase in the proximity of domain walls. Combined with first-principles theory plus mean field effective Hamiltonian methods, we demonstrate the variability in the polar order parameter, which is stabilized by an increase in the magnitude of the configurational entropy. This study presents a powerful tool to quantify entropy from atomic displacements and demonstrates its dominant role in local symmetry breaking at finite temperatures in classic, nominally Ising ferroelectrics.

Original languageEnglish (US)
Article number104102
JournalPhysical Review B
Volume100
Issue number10
DOIs
StatePublished - Sep 3 2019

Fingerprint

Entropy
entropy
Niobium
niobium
Ferroelectric materials
Oxygen
Hamiltonians
Mean field theory
Galaxies
Domain walls
Calorimetry
Aberrations
domain wall
proximity
aberration
oxygen atoms
broken symmetry
heat measurement
Single crystals
Thermodynamics

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Mukherjee, Debangshu ; Prokhorenko, Sergei ; Miao, Leixin ; Wang, Ke ; Bousquet, Eric ; Gopalan, Venkatraman ; Alem, Nasim. / Atomic-scale measurement of polar entropy. In: Physical Review B. 2019 ; Vol. 100, No. 10.
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Mukherjee, D, Prokhorenko, S, Miao, L, Wang, K, Bousquet, E, Gopalan, V & Alem, N 2019, 'Atomic-scale measurement of polar entropy', Physical Review B, vol. 100, no. 10, 104102. https://doi.org/10.1103/PhysRevB.100.104102

Atomic-scale measurement of polar entropy. / Mukherjee, Debangshu; Prokhorenko, Sergei; Miao, Leixin; Wang, Ke; Bousquet, Eric; Gopalan, Venkatraman; Alem, Nasim.

In: Physical Review B, Vol. 100, No. 10, 104102, 03.09.2019.

Research output: Contribution to journalArticle

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Mukherjee D, Prokhorenko S, Miao L, Wang K, Bousquet E, Gopalan V et al. Atomic-scale measurement of polar entropy. Physical Review B. 2019 Sep 3;100(10). 104102. https://doi.org/10.1103/PhysRevB.100.104102