Colossal magnetoresistance

About: Colossal magnetoresistance is a research topic. Over the lifetime, 3658 publications have been published within this topic receiving 130104 citations.

Magnetoresistance of single molecular junctions measured by a mechanically controllable break junction method

Abstract: The magnetoresistance of Ni/single benzene-1,4-dithiol/Ni molecular junctions was measured by a mechanically controllable break junction method under a magnetic field. The negative magnetoresistance of the molecular junction as large as 30% and the anisotropic magnetoresistance of atomic contacts and tunnel junctions of Ni as large as 30% were observed.

Magnetic permeability imaging of metals with a scanning near-field microwave microscope

Abstract: We describe a scanning near-field microwave microscope which uses a loop probe to measure local magnetic properties of metallic samples on a length scale of 200 μm. We demonstrate imaging at 6 GHz through spatiallyresolved ferromagnetic resonance experiments on a single crystal of the colossal magneto-resistive material La0.8Sr0.2MnO3. We find the experimental results are qualitatively and quantitatively well described by a simple model of the system.

Large magnetic entropy change above 300 K in a colossal magnetoresistive material La0.7Sr0.3Mn0.98Ni0.02O3

Abstract: A thorough study of the magnetocaloric effect (MCE) in a colossal magnetoresistive compound of La0.7Sr0.3Mn0.98Ni0.02O3 has been made. The large magnetic entropy change of 7.65 J∕kg K upon an applied field of 70 kOe has been found to occur at 350 K, which allows magnetic refrigeration at room temperature. It is interesting to note that, even in high magnetic fields, the magnetic entropy change versus temperature distribution is much more uniform than that of gadolinium and several polycrystalline perovskite manganites, which is desirable for an Ericson-cycle magnetic refrigerator. It is found that such a small amount (∼2%) of substitution of Mn3+ by a magnetic ion (Ni3+ or Co3+) in the perovskite manganite can favor the spin order and hence the MCE. Undoubtedly, this observation opens a window to explore the active magnetic refrigeration at high temperatures.

Magnetic and electrical transport properties of La0.67Ca0.33MnO3 (LCMO):xZnO composites

Abstract: We have synthesized La0.67Ca0.33MnO3 (LCMO):xZnO () composites through a citrate gel route and have characterized them for magnetic and magnetotransport properties. In lower concentrations (), ZnO mostly goes into the perovskite lattice substituting Mn in LCMO and segregates less in the grain boundary region, but at higher concentration (x>0.13) it segregates mostly at the grain boundaries of LCMO and influences the transport properties significantly. A model is proposed which describes the overall resistivity of the system as a parallel combination of a low resistive intragrain conducting path and a high resistive intergrain insulating path. Using this approach, the grain and grain boundary contributions to the overall resistivity are separated for all the composites. The field dependent resistivity shows that all the composites have higher values of MR at the transition temperatures (TMI) compared to that in pure LCMO (x = 0). The highest value of MR is obtained for x = 0.10 and is 76.6% at 80 kOe field near TMI.