QUANTUM OSCILLATIONS, TUNNELING MAGNETORESISTANCE AND ANGULAR DEPENDENCE OF MAGNETIZATION IN Ca3Ru2O7

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3251-3251
Author(s):  
G. CAO
Keyword(s):  
Angular Dependence ◽  
Metallic Phase ◽  
Tunneling Magnetoresistance ◽  
Electronic Transitions ◽  
Orthorhombic Structure ◽  
Quantum Oscillations ◽  
Antiferromagnetic Ordering ◽  
Wide Range ◽  
Spin Charge Coupling ◽  
Strong Spin

Ca3Ru2O7 has a double Ru-O layered orthorhombic structure. It is a "bad" metal characterized by various abrupt magnetic and electronic transitions that are highly anisotropic. Ca3Ru2O7 undergoes antiferromagnetic ordering at TN = 56 K and a metal to poorer metal transition at TM = 48 K with a unique antiferromagnetic metallic phase intermediate between the paramagnetic and antiferromagnetic phases. Our recent study reveals a few more striking features: (1) Quantum oscillations, i.e., the Shubnikov-de Haas effect, of which the fast Fourier transform shows two frequencies F1 = 23.4 and F2 = 41 tesla, respectively; (2) Inter-plane tunneling magnetoresistance, whose ratio is more than 90% [ρ(0) - ρ(H)/ρ(0)]; (3) Anomalous angular dependence of magnetization, which leads to similar angular dependence of resistivity due to a strong spin-charge coupling. Ca3Ru2O7 is a rare system that possesses a wide range of interesting yet complex physical properties that very often do not coexist in other materials. The results and discussions will be presented along with comparisons with other related systems.

Magnetic Quantum Oscillations from Surface States of Bi Nanowires

2011 ◽  
Vol 1350 ◽  
Author(s):  
L. A. Konopko ◽  
T. E. Huber ◽  
A. A. Nikolaeva
Keyword(s):  
Single Crystal ◽  
Low Temperatures ◽  
Surface States ◽  
Charge Carriers ◽  
Quantum Oscillations ◽  
Wide Range ◽  
Spin Orbit Interactions ◽  
Conducting Tube ◽  
Magnetic Quantum Oscillations ◽  
Strong Spin

ABSTRACTIn this work, we report the results of studies of the transverse magnetoresistance (MR) of single-crystal Bi nanowires with diameter d<80 nm. The single-crystal nanowire samples were prepared by the Taylor-Ulitovsky technique. Due to the semimetal-to-semiconductor transformation and high density of surface states with strong spin-orbit interactions, the charge carriers are confined to the conducting tube made of surface states. The non monotonic changes of transverse MR that are equidistant in a direct magnetic field were observed at low temperatures in a wide range of magnetic fields up to 14 T. The period of oscillations depends on the wire diameter d as for the case of longitudinal MR. An interpretation of transverse MR oscillations is presented.

scholarly journals Robust anomalous metallic states and vestiges of self-duality in two-dimensional granular In-InOx composites

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Xinyang Zhang ◽  
Bar Hen ◽  
Alexander Palevski ◽  
Aharon Kapitulnik
Keyword(s):  
Magnetic Field ◽  
Metallic Phase ◽  
Broadband Noise ◽  
Two Dimensional ◽  
Conventional Theory ◽  
Logarithmic Divergence ◽  
Self Duality ◽  
Low Field ◽  
Wide Range ◽  
Low Temperature Resistance

AbstractMany experiments investigating magnetic-field tuned superconductor-insulator transition (H-SIT) often exhibit low-temperature resistance saturation, which is interpreted as an anomalous metallic phase emerging from a ‘failed superconductor’, thus challenging conventional theory. Here we study a random granular array of indium islands grown on a gateable layer of indium-oxide. By tuning the intergrain couplings, we reveal a wide range of magnetic fields where resistance saturation is observed, under conditions of careful electromagnetic filtering and within a wide range of linear response. Exposure to external broadband noise or microwave radiation is shown to strengthen the tendency of superconductivity, where at low field a global superconducting phase is restored. Increasing magnetic field unveils an ‘avoided H-SIT’ that exhibits granularity-induced logarithmic divergence of the resistance/conductance above/below that transition, pointing to possible vestiges of the original emergent duality observed in a true H-SIT. We conclude that anomalous metallic phase is intimately associated with inherent inhomogeneities, exhibiting robust behavior at attainable temperatures for strongly granular two-dimensional systems.

scholarly journals Spin Polarized Transport in an AC-Driven Quantum Curved Nanowire

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Walid A. Zein ◽  
Nabil A. Ibrahim ◽  
Adel H. Phillips
Keyword(s):  
Spin Polarization ◽  
Small Strain ◽  
Oscillatory Behavior ◽  
Tunneling Magnetoresistance ◽  
Mass Approximation ◽  
Wide Range ◽  
Spin Polarized ◽  
Polarized Transport ◽  
The One ◽  
Spin Polarized Transport

Using the effective-mass approximation method, and Floquet theory, we study the spin transport characteristics through a curved quantum nanowire. The spin polarization, P, and the tunneling magnetoresistance, TMR, are deduced under the effect of microwave and infrared radiations of wide range of frequencies. The results show an oscillatory behavior of both the spin polarization and the tunneling magnetoresistance. This is due to Fano-type resonance and the interplay between the strength of spin-orbit coupling and the photons in the subbands of the one-dimensional nanowire. The present results show that this investigation is very important, and the present device might be used to be a sensor for small strain in semiconductor nanostructures and photodetector.

Spin Fluctuation Effect on Electrical Resistivity of La0.8Ca0.2MnO3 Manganite Nanoparticles

2015 ◽  
Vol 14 (04) ◽  
pp. 1550010 ◽  
Author(s):  
K. K. Choudhary
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Regime ◽  
Spin Fluctuation ◽  
Metallic Phase ◽  
Spin Fluctuations ◽  
Electron Interaction ◽  
Manganite Nanoparticles ◽  
Wide Range ◽  
Insulating Phase

The electrical resistivity ρ(T) of La 0.8 C 0.2 MnO 3 manganite nanoparticles (particle size 18 nm and 70 nm) significantly depends on temperature and size of nanoparticles. ρ(T) of 70 nm La 0.8 C 0.2 MnO 3 manganite exhibits metallic phase in low temperature regime (T < 250 K ), develops a maxima near 250 K and decrease with T at high temperatures (250 K < T < 300 K ). However, the ρ(T) of 18 nm La 0.8 C 0.2 MnO 3 manganite shows insulating phase in overall temperature regime, where resistivity decrease with temperature. The resistivity in metallic phase is theoretically analyzed by considering the strong spin fluctuations effect which is modelled using Drude–Lorentz type function. In addition to the spin fluctuation-induced contribution the electron-phonon and electron-electron ρe-e(T) = BT2 contributions are also incorporated for complete understanding of experimental data. The contributions to the resistivity by inherent acoustic phonons (ρac) as well as high frequency optical phonons (ρop) were estimated using Bloch–Gruneisen [BG] model of resistivity. It is observed that the resistivity contribution due to electron-electron interaction shows typical quadratic temperature dependence. Resistivity in Semiconducting/insulating phase is discussed with small polaron conduction (SPC) model. Finally the theoretically calculated resistivity compared with experimental data which found consistent in wide range of temperature.

scholarly journals Direct Observation of Decoupled Structural and Electronic Transitions and an Ambient Pressure Monocliniclike Metallic Phase ofVO2

2014 ◽  
Vol 113 (21) ◽  
Author(s):  
J. Laverock ◽  
S. Kittiwatanakul ◽  
A. A. Zakharov ◽  
Y. R. Niu ◽  
B. Chen ◽  
...  
Keyword(s):  
Direct Observation ◽  
Ambient Pressure ◽  
Metallic Phase ◽  
Electronic Transitions

Strong spin frustration and negative magnetization in LnCu3(OH)6Cl3 (Ln = Nd and Sm) with triangular lattices: the effects of lanthanides

2017 ◽  
Vol 46 (29) ◽  
pp. 9535-9541 ◽  
Author(s):  
Wei Sun ◽  
Ya-Xi Huang ◽  
Yuanming Pan ◽  
Jin-Xiao Mi
Keyword(s):  
Spin Frustration ◽  
Antiferromagnetic Ordering ◽  
Negative Magnetization ◽  
Triangular Lattices ◽  
Strong Spin

New triangular lattices of LnCu3(OH)6Cl3 (Ln = Nd and Sm) feature canted antiferromagnetic ordering and negative magnetization.

A characterization and catalytic study of Y zeolite supported Ni/Cu bimetallics

1990 ◽  
Vol 68 (9) ◽  
pp. 1471-1476 ◽  
Author(s):  
Brendan Coughlan ◽  
Mark A. Keane
Keyword(s):  
Reduction Process ◽  
Transition Metal Ions ◽  
Metallic Phase ◽  
Hydrogen Atmosphere ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Zeolite Framework ◽  
Wide Range ◽  
Flowing Hydrogen ◽  
Supported Ni

A wide range of CuNiNaY andCuNiKY zeolites were prepared by ion exchange. The location of both Ni2+ and Cu2+ cations within the zeolite framework was monitored after various stages of thermal treatment and the reduction process of the transition metal ions in a flowing hydrogen atmosphere was investigated and correlated with reduction time and temperature. The metallic phase generated on reduction was characterized by X-ray diffraction line broadening. The catalytic activity of the reduced zeolites in the hydrogenation of benzene is discussed in the light of these physical characterizations.Keywords: zeolites, supported Ni/Cu bimetals, cation location, crystallite size, catalysis.

MAGNETIC FLUCTUATIONS IN METALLIC AND SUPERCONDUCTING La2−xSrxCuO4

1992 ◽  
Vol 06 (05n06) ◽  
pp. 451-452
Author(s):  
G. AEPPLI
Keyword(s):  
Fermi Surface ◽  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Mean Free Path ◽  
Inelastic Neutron ◽  
Metallic Phase ◽  
Magnetic Fluctuations ◽  
Relaxation Rates ◽  
Antiferromagnetic Ordering ◽  
The Many

The full momentum and energy dependent magnetic susceptibility χ(Q, ω) is a fundamental quantity which determines many readily measured properties, such as bulk susceptibilities and nuclear magnetic relaxation rates. Because there is still no agreement on the origin of the many anomalous properties of the high-Tc compounds, we have used inelastic neutron scattering to establish χ(Q, ω) in insulating metallic and superconducting samples of La 2−x Sr x CuO 4, arguably the simplest of the layered cuprous oxides. For the (x=0) insulator χ(Q, ω) has been determined throughout the Brioullin zone. At ω/ T >1, it is dominated by spin waves with a zone edge energy of 0.312±0.005 eV. (1,2) As x is increased and the metallic phase approached, the long wavelength anitiferromagnetic fluctuations become more rapid in a manner consistent with the marginal Fermi liquid Ansatz.(3) Finally, for the most metallic samples, the peak in the magnetic response found in the insulator at (π,π) (the antiferromagnetic ordering vector of pure La 2 CuO 4) splits into four maxima.(4) The correlation length at (π,π)±(π,0)δ and (π,π)±(0,π)δ does not depend strongly on x, and for x=0.14, is considerably longer than the spacing between holes in the CuO2 planes. However, ξ is strongly temperature-dependent, in contrast to what occurs for more insulating (lower x) crystals. Taken together, the results can be taken as evidence for the emergence of a Fermi surface, with the incommensurabilities corresponding to nesting vectors, and ξ corresponding to a mean free path for the carriers. In other words, the neutron scattering measurement is giving information of a type ordinarily yielded by de Haas van Alphen data. While the relatively large values for δ are inconsistent with single-band models for the CuO 2 planes, P. Littlewood and collaborators(5) have shown that Fermi surface nesting in a multiband model with reasonable hopping parameters can account for the observations at low temperatures.

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