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Title: Glass-Like Through-Plane Thermal Conductivity Induced by Oxygen Vacancies in Nanoscale Epitaxial La 0.5Sr 0.5CoO 3– δ [Glass-Like Thermal Conductivity Induced by Oxygen Vacancies in Nanoscale Epitaxial La 0.5Sr 0.5CoO 3– δ]

Here, ultrafast time-domain thermoreflectance (TDTR) is utilized to extract the through-plane thermal conductivity (Λ LSCO) of epitaxial La 0.5Sr 0.5CoO 3–δ (LSCO) of varying thickness (<20 nm) on LaAlO 3 and SrTiO 3 substrates. These LSCO films possess ordered oxygen vacancies as the primary means of lattice mismatch accommodation with the substrate, which induces compressive/tensile strain and thus controls the orientation of the oxygen vacancy ordering (OVO). TDTR results demonstrate that the room-temperature Λ LSCO of LSCO on both substrates (1.7 W m –1 K –1) are nearly a factor of four lower than that of bulk single-crystal LSCO (6.2 W m –1 K –1). Remarkably, this approaches the lower limit of amorphous oxides (e.g., 1.3 W m –1 K –1 for glass), with no dependence on the OVO orientation. Through theoretical simulations, origins of the glass-like thermal conductivity of LSCO are revealed as a combined effect resulting from oxygen vacancies (the dominant factor), Sr substitution, size effects, and the weak electron/phonon coupling within the LSCO film. The absence of OVO dependence in the measured Λ LSCO is rationalized by two main effects: (1) the nearly isotropic phononic thermal conductivity resulting from the imperfect OVO planes when δ is small;more » (2) the missing electronic contribution to Λ LSCO along the through-plane direction for these ultrathin LSCO films on insulating substrates.« less
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [4] ;  [4] ;  [2] ;  [1] ;  [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States)
  2. Purdue Univ., West Lafayette, IN (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Univ. Complutense de Madrid, Madrid (Spain)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FG02-06ER46275; SC0016371
Accepted Manuscript
Journal Name:
Advanced Functional Materials
Additional Journal Information:
Journal Volume: 27; Journal Issue: 47; Journal ID: ISSN 1616-301X
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF); Spanish Ministerio de Economia y Competitividad (MINECO); USDOE
Country of Publication:
United States
36 MATERIALS SCIENCE; Boltzmann transport equation; LSCO; TDTR; molecular dynamics simulation; nanoscale epitaxial LSCO; oxygen vacancies; perovskite; thermal conductivity; time-domain thermoreflectance
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1407813