First-order transition and phase separation in pyrochlores with colossal magnetoresistance

2001/11/08 by P. Olalde-Velasco, P. Velasco, J. Mira +7 · 2 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Multiferroics and related materials #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevb.66.104412

6 pages. Figures included

arxiv created 2001/11/08 · openalex publication_date 2002/09/16 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Tl₂Mn₂O₇ pyrochlores present colossal magnetoresistance (CMR) around the long-range ferromagnetic ordering temperature (T_C). The character of this magnetic phase transition has been determined to be first order, by purely magnetic methods, in contrast to the second order character previously reported by Zhao et al. [Phys. Rev. Lett. 83, 219 (1999)]. The highest CMR effect, as in Tl_1.8Cd_0.2Mn₂O₇, corresponds to a stronger first order character. This character implies a second type of magnetic interaction, in addition to the direct superexchange between the Mn⁴⁺ ions, as well as a phase coexistence. A model is proposed, with a complete Hamiltonian (including superexchange and an indirect interaction), which reproduce the observed phenomenology.

Citations

• Phase separation and enhanced charge-spin coupling near magnetic transitions
• On a generalised approach to first and second order magnetic transitions

Cited by

• Phase Coexistence and Resistivity near the Ferromagnetic Transition of Manganites
• Mott-Hubbard quantum criticality in paramagnetic CMR pyrochlores