Colossal magnetoresistance

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

Ferromagnetic enhancement of CE-type spin ordering in (Pr,Ca)MnO3.

Abstract: We present resonant soft x-ray scattering results from small bandwidth manganites $(\mathrm{Pr},\mathrm{Ca}){\mathrm{MnO}}_{3}$, which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic state and CE-type ordering.

Local and average crystal structure and displacements of La 11 B 6 and EuB 6 as a function of temperature

Abstract: Measurements of both the average crystal structure from Rietveld refinement of neutron powder diffraction (NPD) data and the local structure from La L{sub III}-edge x-ray-absorption fine-structure (XAFS) are presented for a La{sup 11}B{sub 6} sample as a function of temperature ({approx}10-320 K). These data are compared to XAFS results on a EuB{sub 6} sample. The single-site La and B positional distribution widths and the La-B and La-La bond length distribution widths and their temperature dependence are compared. This comparison allows an estimate of the La and B site displacements, and we find that these sublattices are only slightly correlated with each other. Moreover, while the temperature dependence of the displacement parameters of the average sites from diffraction fit an Einstein model well, the temperature dependence of the La-B bond length distribution width requires at least two vibrational frequencies, corresponding to the La and B frequencies of the individual sites. XAFS data on EuB{sub 6} indicate that the situation is the same in the Eu compound. In addition, comparisons between data taken below and above the ferromagnetic transition temperature for EuB{sub 6} place stringent limits on the lattice involvement in the associated metal-insulator transition and the ensuing large magnetoresistance effect. This lack of lattice involvement in the magnetoresistance transition is in sharp contrast to the strong lattice involvement observed in the colossal magnetoresistance lanthanum manganese perovskites.

Synthesis of La0.7Sr0.3MnO3 materials by versatile chemical technique

Abstract: We have developed a simple low-cost novel synthesis route to synthesize nanosized La 0.7 Sr 0.3 MnO 3 (LSMO) without any requirement of a calcinations step at high temperature. The study of these nanoparticles indicates excellent properties (magnetization and resistance at 0 T) similar to colossal magnetoresistance (CMR) materials sintered at 1600 °C for 20 h. The size and topography of the oxides are dependent on the calcinating temperature of the precursors. The resulting particle size is in the range of 20–100 nm as determined by transmission electron microscopy. The magnetization of LSMO nanophase is strikingly dependent on the particle size. The transition temperature from the paramagnetic to ferromagnetic state of the sample is quite sharp and occurs at 372 K for 600 °C calcined sample sintered at 1200 °C for 4 h. Magnetoresistance of magnitude −5.7% at the field up to 1 T was also observed at room temperature.

Crossover of angular dependent magnetoresistance with the metal-insulator transition in colossal magnetoresistive manganite films

Abstract: The temperature and magnetic field dependence of angular dependent magnetoresistance (AMR) along two orthogonal directions ([100] and [01¯1]) was investigated in a charge-orbital-ordered Sm0.5Ca0.5MnO3 (SCMO) film grown on (011)-oriented SrTiO3 substrates. A dramatic decrease of AMR magnitude in both directions was observed with the appearance of magnetic-field-induced metal-insulator transition, which further led to a sign crossover in the AMR effect. The AMR crossover may give a direct evidence of the drastic modification of electronic structure or possible orbital reconstruction with the magnetic-destruction of charge/orbital ordering in SCMO films.

Colossal magnetoresistance via avoiding fully polarized magnetization in the ferrimagnetic insulator Mn 3 Si 2 Te 6

Abstract: 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 materials. The stoichiometric Mn3Si2Te6 is an insulator featuring a ferrimagnetic transition at 78 K. The resistivity drops by 7 orders of magnitude with an applied magnetic field above 9 Tesla, leading to an insulator-metal transition at up to 130 K. However, the colossal magnetoresistance occurs only when the magnetic field is applied along the magnetic hard axis and is surprisingly absent when the magnetic field is applied along the magnetic easy axis where magnetization is fully saturated. The anisotropy field separating the easy and hard axes is 13 Tesla, unexpected for the Mn ions with nominally negligible orbital momentum and spin-orbit interactions. Double exchange and Jahn-Teller distortions that drive the hole-doped manganites do not exist in Mn3Si2Te6. The phenomena fit no existing models, suggesting a unique, intriguing type of electrical transport.