Spontaneous magnetoresistance

Figure 1 Spontaneous magnetoresistance anisotropy Ap of Feo.2Nio g as a function of the scaling parameters (cq/c) (o) and ( ). The experimental value is that from to Jaoul et al. [9j.

Figure 5.13 Isotropic residual resistivity p (left), and spontaneous magnetoresistance anisotropy ratio A p/p (right) of disordered BCC-Fe Coj alloys calculated in four different...

Cu and Mn, systems that have partially filled d shells with a degenerate ground state. According to the Jahn-Teller theorem, any degenerate electronic system will spontaneously distort in such a way as to remove the degeneracy (Dunitz and Orgel 1960). The distortions around Cu " have been extensively studied and may play a role in the superconductivity found in some copper oxides (Section 13.3.2), while the distortions around Mn + play an important role in the potentially useful magnetoresistive properties of LaMnOs (Section 13.3.3). 

It is clear that the metaelasticity similar to the observed one in the rare-earth compounds is present in the colossal magnetoresistance systems. The results of the corresponding behavior of the uniaxial spontaneous strain depending upon the uni-... 

Fig. 6.43. The magnetoresistance of gadolinium at 205 K, showing the spontaneous anisotropy described in section 6.1 and the linear negative magnetoresistance discussed in section 6.2. The arrows indicate the applied field needed to create a single domain in the two configurations (after McEwen and Webber 1976).

---