2001/03/22 by B. M. Letfulov, J. K. Freericks · 2 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Ising model #Magnetic and transport properties of perovskites and related materials #Magnetic field #Magnetoresistance #Mean field theory #Phase (matter) #Phase diagram #Phase transition #Physics #Quantum mechanics #Spins #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.64.174409
published as Phys. Rev. B 64, 174409 (2001) · 14 pages, 10 figures, ReVTeX
arxiv created 2001/03/22 · openalex publication_date 2001/10/03 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a simplified model for the colossal magnetoresistance in doped manganites by exactly solving a double-exchange model (with Ising-like local spins) and quenched binary disorder within dynamical mean field theory. We examine the magnetic properties and the electrical and thermal transport. Our solution illustrates three different physical regimes: (i) a weak-disorder regime, where the system acts like a renormalized double-exchange system (which is insufficient to describe the behavior in the manganites); (ii) a strong-disorder regime, where the system is described by strong-coupling physics about an insulating phase (which is the most favorable for large magnetoresistance); and (iii) a transition region of moderate disorder, where both double-exchange and strong disorder effects are important. We use the thermopower as a stringent test for the applicability of this model to the manganites and find that the model is unable to properly account for the sign change of the thermopower seen in experiment.