Magnetic and Structural Phase Transitions of EuFe2As2 Studied via Neutron and Resonant X-ray Scattering

• Published in: Journal of the Physical Society of Japan Vol. 79; no. 11; pp. 114708 - 114708-6
• Main Authors: Koo, Japil, Park, Jihwey, Cho, Sung Kook, Kim, Ki Duk, Park, Sang-Youn, Jeong, Yoon Hee, Park, Yong Jun, Koo, Tae Yeong, Hong, Kun-Pyo, Lee, Chang-Hee, Kim, Ju-Young, Cho, Beong-Ki, Lee, Ki Bong, Kim, Heon-Jung
• Format: Journal Article
• Language: English
• Published: Tokyo The Physical Society of Japan 01-11-2010; Physical Society of Japan
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Halides, chalcogenides and analogous compounds of group vb; Inorganic compounds; Magnetic properties and materials; Physics; Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.); Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Universality class; Integrated intensity; neutron and resonant x-ray scattering; Phase transformations; Magnetic ordering; Order parameters; Iron Europium Arsenides Mixed; Magnetic transitions; Free energy; EuFe; Pnictides; X-ray scattering; Resonance scattering; Monocrystals; As; coupling between structural and magnetic order parameters; Iron based arsenide; Crystal structure
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/JPSJ.79.114708

Employing neutron and resonant x-ray scatterings, we have investigated the magnetic and structural phase transitions of a high quality single crystal of undoped pnictide EuFe 2 As 2 to reveal the nature of these transitions. It has been found that structural order parameter $\delta=(a-b)/(a+b)$ and the square of Fe magnetic order parameter have the same temperature dependence, which is attributed to the linear-quadratic coupling between structural and Fe magnetic order parameters in the Landau free-energy expansion. This result also suggests that Fe magnetic order drives the structural phase transition which is the weak first-order phase transition.