相关论文: Mapping Colossal Magnetoresistance Phase Transitio…
A novel ferromagnetic transition, accompanied by carrier density collapse, is found in doped charge-transfer insulators with strong electron-phonon coupling. The transition is driven by an exchange interaction of polaronic carriers with…
The exchange interaction of polaronic carriers with localized spins leads to a ferromagnetic/paramagnetic transition in doped charge-transfer insulators with strong electron-phonon coupling. The relative strength of the exchange and…
Colossal magnetoresistance (CMR) is associated with the phase transition from a metallic ferromagnetic to insulating paramagnetic phase, which can be controlled by an applied magnetic field. The insulating phase occurs due to trapping of…
We investigated magnetic and magnetocaloric properties in Sm1-xSrxMnO3 (x = 0.30-0.5). We report a magnetic field driven first-order metamagnetic transition in the paramagnetic state in x = 0.4 and 0.5 and a second-order transition in x =…
Pairing of oxygen holes into heavy bipolarons in the paramagnetic phase and their magnetic pair-breaking in the ferromagnetic phase [the so-called current-carrier density collapse (CCDC)] has accounted for the first-order ferromagnetic…
Measurements of Seebeck effect in 0 and 1.5 T and Nernst coefficient in 0.3,0.9 and 1.8 T as a function of temperature on a polycrystalline sample Sm0.55Sr0.45MnO3 are presented. The data point out conclusively that an increase inboth the…
Colossal enhancement of magnetoresistance has been achieved over a broad temperature range which extends upto the room temperature, in ferromagnetic metal-charge ordered insulator manganite multi-layers. The artificially created phase…
Extensive experimental results are presented on the multi-scale phase modulation phenomena observed in colossal magnetoresistance manganites. Two key types of phase inhomogeneities directly relevant to the colossal magnetoresistance (CMR)…
We show that the current carrier density collapse in doped manganites, which results from bipolaron formation in the paramagnetic phase, leads to a colossal change of the optical conductivity in an external magnetic field at temperatures…
We present a small-but-sizeable magnetic polaron picture where transport at high temperatures is activated while at low temperatures it is band-like. We show that both double exchange and finite bandwidth effects are important to understand…
The metallic or insulating nature of the paramagnetic phase of the colossal-magnetoresistance manganites is investigated via a double exchange Hamiltonian with diagonal disorder. Mobility edge trajectory is determined with the transfer…
The colossal electroresistance in manganites is a concomitant of the electric field induced insulator-to-metal phase transition. A phenomenological phase transition model is proposed to study this electric field induced collapse of…
1% $^{119}$Sn-doped La$_{0.5}$Ca$_{0.5}$MnO$_3$ was studied by M\"ossbauer spectroscopy, magnetic moment and resistivity measurements. The M\"ossbauer spectra below the charge-ordering temperature are explained with ferromagnetic (FM),…
It is shown that with increasing magnitude of current (I), resistivity of Sm0.6Sr0.4MnO3 transforms from a smooth to a discontinuous insulator-metal transition which is also accompanied by an abrupt decrease in temperature of the sample. We…
The temperature dependence of the electronic and atomic structure of the colossal magnetoresistive oxides $La_{1-x}Sr_{x}MnO_{3}$ (x = 0.3, 0.4) has been studied using core and valence level photoemission, x-ray absorption and emission, and…
We have studied the low-frequency dielectric properties of the phase-separated manganite Pr0.7Ca0.3MnO3 as a function of applied magnetic field in the low temperature phase-separated state. The dielectric constant is strongly field…
Colossal magnetoresistance is of great fundamental and technological significance and exists mostly in the manganites and a few other materials. Here we report colossal magnetoresistance that is starkly different from that in all other…
We have investigated the specific heat and resistivity of a single crystal of Pr_{0.63}Ca_{0.37}MnO_3 around the charge ordering (CO) transition temperature, T_{CO}, in the presence of high magnetic fields (<=12T) which can melt the charge…
We explore the possibility that polaronic distortions in the paramagnetic phase of La$_{0.67}$Ca$_{0.33}$MnO$_3$ manganites persist in the ferromagnetic phase by considering the observed electrical resistivity to arise from coexisting…
The phase diagram of Pr0.65(CaySr1-y)0.35MnO3, 0.6 <= y <= 0.8, has been determined by neutron diffraction, magnetization and electrical conductivity measurements in order to investigate the nature of the transition between ferromagnetic…