Pressure Tuning of Electron-Phonon Coupling: The Insulator to Metal Transition in Manganites

Abstract

An extended temperature and pressure-dependent investigation is carried out on a La0.75Ca0.25MnO3 sample exploiting the infrared absorption technique coupled to a diamond anvil cell. The pressure dependence of the insulator to metal transition temperature T(IM) is determined for the first time up to 11.2 GPa. The T(IM)(P) curve we propose to model the present data has an exponential-like behavior with an associated characteristic pressure P* playing the role of a decay constant. It is found that the equivalence between an external and an internal (chemical) pressure holds over a limited range of pressure, namely, P< or =2P*. Moreover, a certain universality character is associated with the proposed model curve in its ability to account for a large class of low-disorder manganites characterized by intermediate electron-phonon coupling.

Unusual Mott transition in multiferroic PbCrO 3

“…Coupled with the metallization process, the transition of polarons from localized states into the continuum gives rise to a broad band located in near-infrared (IR) region (40). Therefore, the delocalization of polarons can be probed by the IR spectroscopy.…”

“…The pressure-dependent spectral weight (Fig. 4B, Inset), n*, which is a frequency-integrated absorbance at 3,800-6,400 cm -1 , provides a measure of polaron mobility (40,41). Upon initial compression, the broadband optical density, O d (ω), and n* decrease with increasing pressures.…”

“…The insulator-metal transition can further be determined using the optical method and understood in terms of the polaron theory (40,41). Coupled with the metallization process, the transition of polarons from localized states into the continuum gives rise to a broad band located in near-infrared (IR) region (40).…”

Electronic phase separation and other novel phenomena and properties exhibited by mixed-valent rare-earth manganites and related materials

“…The second possibility is the presence of long-range elastic strain fields which are unscreened. Indeed, it is well known that pressure (strain) can drive transitions in the manganites Postorino et al 2003). The key question is whether strain effects are extrinsic (caused by defects, etc.)…”

Influence of Pellet Compaction Pressure on the Physical Properties of La0.7Ba0.3MnO3 Manganite

“…Usually this variation leads to an increase in electron bandwidth that can strongly modify the Curie temperature and the metal-to-insulator transition temperature as well as decreasing the resistivity 12,13 . Reported studies in the literature show that manganite properties such as insulator to metal transition temperature T IM , Curie temperature (T C ), charge ordering (CO) and magnetization can have a strong dependence on an applied hydrostatic pressure [13][14][15][16][17] . Although several studies have been carried out on manganites as a function of hydrostatic pressure, we have not found any paper reporting studies on the effect of compaction pressure on the physical properties of the pellet samples.…”