Colossal magnetoresistance

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

Tunneling Evidence of Half-Metallic Ferromagnetism in La(0.7)Ca(0.3)MnO(3)

Abstract: Direct experimental evidence of half-metallic density of states (DOS) is observed by scanning tunneling spectroscopy on ferromagnetic La(0.7)Ca(0.3)MnO(3) which exhibits colossal magnetoresistance (SMR).

Large room-temperature magnetoresistance and phase separation in La1−xNaxMnO3 with 0.1⩽x⩽0.3

Abstract: The structural, magnetic, and electronic properties of the polycrystalline La1−xNaxMnO3 (x=0.10, 0.15, 0.20, and 0.30) are investigated. The result of the Rietveld refinement of x-ray powder diffraction shows that these compounds crystallize in a rhombohedrally distorted structure with space group R3C. The magnetic measurement shows that Curie temperature TC of the studied samples is near or above room temperature. The temperature dependence of resistivity shows that all samples undergo a sharp transition accompanying a paramagnetic to ferromagnetic with the decrease of temperature, however, for x⩾0.15 samples, double transition peaks with a single ferromagnetic transition is observed. In the meanwhile, a large room-temperature magnetoresistance with low applied magnetic field is observed. The co-existing ferromagnetic metallic phases and ferromagnetic insulating (FMI) phases induced by the electronic inhomogeneity as well as the additional FMI phases caused by the presence of vacancies at the A sites, a...

Gate-controlled linear magnetoresistance in thin Bi2Se3 sheets

Abstract: We explore the emergence of linear magnetoresistance in thin Bi2Se3 sheets upon tuning the carrier density using a back gate. With increasingly negative gate voltage, a pronounced magnetoresistance of ∼100% is observed, while the associated B-field dependence changes from quadratic to linear. Concomitantly, the resistance-versus-temperature curves evolve from metallic to semiconductor-like, and increasingly strong weak anti-localization behavior is manifested. Analysis of the magnetoresistance data reveals two contributions, namely from the bulk conduction band and from a state inside the bulk gap. The latter is responsible for the linear magnetoresistance and likely represents the topologically protected surface state.

Perovskite‐like Mn2O3: A Path to New Manganites

Abstract: Among complex oxides, perovskite-based manganites play a special role in science and technology. They demonstrate colossal magnetoresistance, and can be employed as memory and resistive switching elements or multiferroics. The perovskite structure ABO3 has two different cation sites: B-sites that are octahedrally coordinated by oxygen, and cuboctahedrally-coordinated (often heavily distorted) Asites. The magnetic and transport properties of perovskite manganites are largely determined by the Mn O Mn interactions in the perovskite framework of corner-sharing MnO6 octahedra. Although the A cations do not directly participate in these interactions, they control the Mn valence and the geometry of the Mn O Mn bonds. Complex phenomena, such as charge and orbital ordering, often accompany chemical substitutions on the A-site. Requirements on formal charge and ionic radius are usually different for cations adopting theA or B positions and prevent A/B mixing. Small and often highly charged transition-metal B-cations are unfavorable for the large 12coordinated A-site. Partial filling of the A-position with transition metals is, nevertheless, possible in a unique class of A-site ordered perovskites AA’3B4O12 (where A= alkali, alkali-earth, rare-earth, Pb, or Bi cations, A’=Cu or Mn, and B= transition metals, Ga, Ge, Sb, or Sn). A key ingredient of such compounds is the A’ cation that should be prone to a first-order Jahn–Teller effect (Cu or Mn). An oxygen environment suitable for such transition-metal cations at the A’ position is created by the aaa octahedral tilt system (in Glazer s notation) with a notably large magnitude of the tilt (for example, in CaCu3Ti4O12 the Ti O Ti bond angle is only 140.78). The tilt creates a square-planar anion coordination, favorable for Jahn–Teller-active A’ cations. The ap= ffiffiffi

Extremely large magnetoresistance in few-layer graphene/boron-nitride heterostructures

Abstract: Understanding magnetoresistance, the change in electrical resistance under an external magnetic field, at the atomic level is of great interest both fundamentally and technologically. Graphene and other two-dimensional layered materials provide an unprecedented opportunity to explore magnetoresistance at its nascent stage of structural formation. Here we report an extremely large local magnetoresistance of ∼2,000% at 400 K and a non-local magnetoresistance of >90,000% in an applied magnetic field of 9 T at 300 K in few-layer graphene/boron-nitride heterostructures. The local magnetoresistance is understood to arise from large differential transport parameters, such as the carrier mobility, across various layers of few-layer graphene upon a normal magnetic field, whereas the non-local magnetoresistance is due to the magnetic field induced Ettingshausen-Nernst effect. Non-local magnetoresistance suggests the possibility of a graphene-based gate tunable thermal switch. In addition, our results demonstrate that graphene heterostructures may be promising for magnetic field sensing applications.