Effects of Mn Substitution on the Thermoelectric Properties and Thermal Excitations of the Electron-doped Perovskite Sr_1−xLa_xTiO₃

Elastic and dynamical structural properties of La and Mn-doped SrTiO3 studied by neutron scattering and their relation with thermal conductivities

“…We found all the compounds exhibit similar values of specific heats at high temperatures (see Supplementary Fig. S1) although doping dependence was reported at low temperatures below 100 K 7,17 . This result indicates that the large reduction of κ in SLTMO2 and SLTMO4 is not caused by the change in C and instead is caused by the decrease in l or v g .…”

“…7 reported that at 300 K, STO, STMO, and SLTO exhibit similar values of κ while SLTMO2 exhibits significantly lower κ , and the latter is approximately half of that for the former three samples. We studied κ in the range of 0 ≤  x  ≤ 0.07 and 0 ≤  y  ≤ 0.04 in Sr 1− x La x Ti 1− y Mn y O 3 , and found that the sample with x  = 0.05 and y  = 0.02 (SLTMO2) gives the lowest κ .…”

“…The high sensitivity of the structural transition on the tolerance factor should reflect that SrTiO 3 is in a structurally critical state. However, it is unlikely that the tetragonal structure in the La-Mn co-doped samples is the origin of the low κ , since the transition in STO to the low-temperature tetragonal structure at T s does not significantly change κ 7 .…”

“…Subsequently, we compared the values of S ( E ) in the low-energy region with the values of κ . Figure 4 shows in the region of E  = 5–10 meV relative to the values of κ at 298 K 7 . The values for STO are subtracted from these values.…”

“…Recently, we found that a few percent co-doping of La and Mn in SrTiO 3 substantially reduces the thermal conductivity at room temperature without significant reduction of the electric conductivity 6,7 . Interestingly, this type of anomaly occurs only when both of La and Mn are doped, and it potentially corresponds to a dynamical effect coupled with carriers.…”