Structural, electronic, and magnetic entropy contributions of the orbital order-disorder transition in LaMnO3

Author(s)

Ramirez, F. E. N. ^[1] ; Cunha, B. B. ^[1] ; Alves, W. A. ^[1] ; Jardim, R. F. ^[2] ; Muccillo, R. ^[3] ; Souza, J. A. ^[1]

Affiliation

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210170 Santo Andre, SP - Brazil

^[2] Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo - Brazil

^[3] IPEN CNEN SP, BR-05422970 Sao Paulo - Brazil

• Document type: Journal article
• Source: PHASE TRANSITIONS; v. 84, n. 3, p. 284-290, 2011.
• Web of Science Citations: 1

Abstract

Measurements of X-ray diffraction, electrical resistivity, and magnetization are reported across the Jahn-Teller phase transition in LaMnO(3). Using a thermodynamic equation, we obtained the pressure derivative of the critical temperature (T(JT)), dT(JT)/dP = -28.3 K GPa(-1). This approach also reveals that 5.7(3)J(mol K)(-1) comes from the volume change and 0.8(2)J(mol K)(-1) from the magnetic exchange interaction change across the phase transition. Around T(JT), a robust increase in the electrical conductivity takes place and the electronic entropy change, which is assumed to be negligible for the majority of electronic systems, was found to be 1.8(3)J(mol K)(-1). (AU)

• FAPESP's process: 05/53241-9 - Study of intergranular phenomena in ceramic materials
• Grantee: Reginaldo Muccillo
• Support Opportunities: Research Projects - Thematic Grants