scholarly journals Colossal Negative Magnetoresistance Effect in a La1.37Sr1.63Mn2O7 Single Crystal Grown by Laser-Diode-Heated Floating-Zone Technique

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 547
Author(s):  
Si Wu ◽  
Yinghao Zhu ◽  
Junchao Xia ◽  
Pengfei Zhou ◽  
Haiyong Ni ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Laser Diode ◽  
Room Temperature ◽  
Floating Zone ◽  
Magnetoresistance Effect ◽  
X Ray ◽  
Mr Effect ◽  
Distinct Features ◽  
The Magnetic Field

We have grown La 1.37 Sr 1.63 Mn 2 O 7 single crystals with a laser-diode-heated floating-zone furnace and studied the crystallinity, structure, and magnetoresistance (MR) effect by in-house X-ray Laue diffraction, X-ray powder diffraction, and resistance measurements. The La 1.37 Sr 1.63 Mn 2 O 7 single crystal crystallizes into a tetragonal structure with space group I4/mmm at room temperature. At 0 T, the maximum resistance centers around ∼166.9 K. Below ∼35.8 K, it displays an insulating character with an increase in resistance upon cooling. An applied magnetic field of B = 7 T strongly suppresses the resistance indicative of a negative MR effect. The minimum MR value equals −91.23% at 7 T and 128.7 K. The magnetic-field-dependent resistance shows distinct features at 1.67, 140, and 322 K, from which we calculated the corresponding MR values. At 14 T and 140 K, the colossal negative MR value is down to −94.04(5)%. We schematically fit the MR values with different models for an ideal describing of the interesting features of the MR value versus B curves.

How the Magnetic Field Impacts the Chiroptical Activities of Helical Copper Enantiomers

2021 ◽  
Author(s):  
jialu wu ◽  
Bo Li ◽  
Hong Wang ◽  
Ying Zhen Lai ◽  
Yue Ye ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solid State ◽  
Thermogravimetric Analysis ◽  
Single Crystal ◽  
Structure Analysis ◽  
Chiral Ligands ◽  
X Ray ◽  
The Magnetic Field

A pair of enantiomers {[Cu(L-pro)(L-tyr)]·2H2O}n (L-1) and {[Cu(D-pro)(D-tyr)]·2H2O}n (D-1) based on the chiral ligands L/D-proline and L/D-tyrosine were synthesized and investigated by single-crystal X-ray structure analysis, IR, thermogravimetric analysis, solid-state...

Influence of Magnetic Field on Magnetic Properties of Electrodeposited Co-Ni-P Nanowires

2014 ◽  
Vol 24 (3S1) ◽  
pp. 90-94 ◽  
Author(s):  
Le Tuan Tu ◽  
Luu Van Thiem ◽  
Pham Duc Thang
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Vibrating Sample Magnetometry ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Structure And Morphology ◽  
The Magnetic Field

The magnetic properties in Co-Ni-P nanowires arrays with diameter of 200 nm were investigated. All the samples were prepared by electrodeposition method with pH of 5.5 and at room temperature. During the deposition, a magnetic field in range of 0 - 750 Oe was applied parallel to the wires axis. The crystalline structure and morphology of the samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), respectively. The hysteresis loops were measured at room temperature using vibrating sample magnetometry (VSM). The mixture of hcp phases of the Co-Ni-P based nanowires has been indicated by the XRD pattern. The obtained results show that with 750 Oe magnetic field applied during deposition we can obtain maximum coercivity value (2180 Oe). The \(M_{r}/M_{s}\) ratio was rapid increased when the magnetic field changed from 0 Oe to 750 Oe.

Magnetic Field Sensors based on Magnetoresistance Effect in Organic Semiconductor Sandwich Devices

2005 ◽  
Vol 906 ◽  
Author(s):  
Govindarajan Veeraraghavan ◽  
Ömer Mermer ◽  
Yugang Sheng ◽  
Tho Duc Nguyen ◽  
Thomas Lee Francis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Organic Semiconductor ◽  
Room Temperature ◽  
Experimental Characterization ◽  
Magnetoresistance Effect ◽  
Temperature Dependent ◽  
Magnetic Field Sensors ◽  
Mr Effect ◽  
Alternating Magnetic Fields

AbstractWe describe magnetic field sensors based on a recently discovered magnetoresistance (MR) effect in nonmagnetic organic semiconductor sandwich devices. The MR effect reaches up to 10% in a magnetic field of 10 mT at room temperature. We perform an extensive experimental characterization of this effect. We found that the MR effect is only weakly temperature dependent and does not depend on sign and direction of the applied magnetic field. We also measured the device response to alternating magnetic fields up to 100 kHz. To the best of our knowledge, the discovered MR effect is not adequately described by any of the MR mechanisms known to date.

Magnetic Properties of CdMoO4:Dy3+ Single Crystal

2016 ◽  
Vol 257 ◽  
pp. 107-110 ◽  
Author(s):  
Tadeusz Groń ◽  
Elzbieta Tomaszewicz ◽  
Marek Berkowski ◽  
Monika Oboz ◽  
Joachim Kusz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Weak Response ◽  
X Ray ◽  
Diamagnetic Transition ◽  
The Magnetic Field

X-ray diffraction measurement at 298 K of CdMoO4:Dy3+ showed that the molybdenum ions are tetrahedral coordinated and Cd/Dy – dodecahedral coordinated. The Dy3+ ions are randomly distributed in the unit cell, substituting the Cd2+ ones. The temperature dependence of ac and dc magnetic susceptibility showed a lack of the Curie-Weiss behaviour and a weak response to the magnetic field. The magnetization isotherms, M(H), showed a paramagnetic-diamagnetic transition at 17 K for 〈100〉 direction and at 35 K for 〈001〉 one in the magnetic field of 70 kOe. As the temperature increased this transition was moving toward smaller magnetic fields.

Synthesis and Magnetic Properties of β-Cu3Fe4(VO4)6 Single Crystals

2015 ◽  
Vol 233-234 ◽  
pp. 137-140
Author(s):  
Dmitry A. Balaev ◽  
Oleg A. Bayukov ◽  
Evgeniy V. Eremin ◽  
M.S. Molokeev ◽  
Anatoly I. Pankrats ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Single Crystal ◽  
Spin Glass ◽  
Single Crystals ◽  
Low Temperatures ◽  
Freezing Temperature ◽  
X Ray ◽  
Glass State ◽  
The Magnetic Field

β-Cu3Fe4(VO4)6 single crystals were synthesized. The X-ray, magnetic, Mössbauer, and EPR investigations of the crystals were fulfilled. It is established that single-crystal β-Cu3Fe4(VO4)6 is a spin glass at low temperatures. Freezing temperature varies considerably depending on the orientation of the magnetic field relative to the crystal axes. Spin-glass state is confirmed by the relaxation of the magnetization.

scholarly journals Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

2009 ◽  
Vol 5 ◽  
Author(s):  
Matthias Lehmann ◽  
Jens Seltmann
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
General Pattern ◽  
Isotropic Phase ◽  
Phenylene Ethynylene ◽  
X Ray ◽  
Step Procedure ◽  
Nematic Phases ◽  
Phase Engineering ◽  
The Magnetic Field

A series of V-shaped, shape-persistent thiadiazole nematogens, based on an oligo(phenylene ethynylene) scaffold with ester groups connected via alkyloxy spacers, was efficiently prepared by a two-step procedure. Phase engineering results in an optimum of the mesophase range and low melting temperature when the nematogens are desymmetrised with a butoxy and a heptyloxy spacer. The mesophases are enantiotropic and over the whole temperature range nematic. For the optimised mesogen structure, optical investigations by conoscopy monitored a uniaxial nematic phase upon cooling from the isotropic phase to room temperature (ΔT = 150 °C). X-ray studies on magnetic-field-aligned samples of this mesogen family revealed a general pattern, indicating the alignment of two molecular axes along individual directors in the magnetic field. These observations may be rationalised with larger assemblies of V-shaped molecules isotropically distributed around the direction of the magnetic field.

Decoration of silicon carbide nanotubes by CoFe2O4 Spinel nanoparticles.

2000 ◽  
Vol 658 ◽  
Author(s):  
Claude Estournès ◽  
Cuong Pham-Huu ◽  
Nicolas Keller ◽  
Marc J. Ledoux
Keyword(s):  
Magnetic Field ◽  
Silicon Carbide ◽  
Room Temperature ◽  
Incipient Wetness Impregnation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silicon Carbide Nanotubes ◽  
Transmission Electron ◽  
The Magnetic Field ◽  
Spinel Nanoparticles

ABSTRACTSilicon carbide nanotubes have been prepared and decorated with CoFe2O4 spinel. These nanocomposites were prepared by incipient wetness impregnation of the dried SiC support with a stoichiometric aqueous solution of the cobalt and iron nitrates. After drying, subsequent annealing treatments were performed under air in the temperature range 873 to 1073 K. X-ray diffraction and high resolution transmission electron microscopy reveal the presence of spinel nanoparticles at the surface of the tubes. Magnetic properties of the nanocomposites show in the magnetic field explored (up to 5 T) that saturation magnetization is not observed neither at room temperature nor at 5Kelvin. The nanometric character and the nature of the spinel particles are also confirmed by the coercive field (1.6 T) observed at low temperature and the curie temperature.

Features Of Magnetoresistance In The Bilayer Single Crystal Manganite LA1.4SR1.6MN2O7

2015 ◽  
Vol 10 (1) ◽  
pp. 63-66
Author(s):  
Stanislav Nikitin ◽  
Sergey Popkov ◽  
Mikhail Petrov ◽  
Konstantin Terent’ev ◽  
Sergey Semenov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Colossal Magnetoresistance ◽  
Transport Current ◽  
Lanthanum Manganite ◽  
Magnetoresistance Effect ◽  
Positive Magnetoresistance ◽  
Lanthanum Manganites ◽  
Colossal Magnetoresistance Effect ◽  
The Magnetic Field

We investigate magnetoresistance of single-crystal bilayer lanthanum manganite La1.4Sr1.6Mn2O7 at a transport current flowing along the crystal c axis and in external magnetic fields applied parallel to the crystal c axis or ab plane. It is demonstrated that the La1.4Sr1.6Mn2O7 manganite exhibits the positive magnetoresistance effect in the magnetic field applied in the ab plane of the sample at the temperatures T < 60 K. The mechanism of this effect is shown to be fundamentally different from the colossal magnetoresistance effect typical of lanthanum manganites. The positive magnetoresistance originates from spin-dependent tunneling of carriers between the manganese-oxygen bilayers and can be explained by features of the magnetic structure of the investigated compounds.

Transport measurements in annealed single crystal tellurium

1970 ◽  
Vol 48 (24) ◽  
pp. 3038-3046 ◽  
Author(s):  
C. H. Champness ◽  
A. L. Kipling
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Room Temperature ◽  
Small Diameter ◽  
Impurity Scattering ◽  
Czochralski Method ◽  
Liquid Nitrogen Temperature ◽  
Carrier Analysis ◽  
The Magnetic Field

Single crystal samples of tellurium obtained from small diameter ingots, specially grown by the Czochralski method from a melt of the purified element, were studied by measuring the electrical conductivity (σ), Hall coefficient (RH), and transverse magnetoresistance (Δρ/ρ0). As a result of annealing and etching, the Hall mobility (RHσ) and Δρ/ρ0 were substantially increased in the samples at liquid nitrogen temperature, while RH was slightly decreased. The samples were completely intrinsic above 250 °K and at room temperature Δρ/ρ0 was strictly proportional to the square of the magnetic field. Like RH and σ at this temperature, it was also independent of sample history. Two-carrier analysis at room temperature gave electron and hole mobilities of 1890 and 790 cm2 V−1 s−1 respectively. At 77 °K, Δρ/ρ0 in the annealed and etched samples was larger than expected for a simple one-carrier model with a mixture of lattice and impurity scattering.

EPR Study of VO2+ and Cr3+ in Li2SO4 · H2O Single Crystal

1997 ◽  
Vol 52 (11) ◽  
pp. 765-770 ◽  
Author(s):  
F. Çelik ◽  
F. Köksal ◽  
İ. Kartal ◽  
H. Gümüş
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Room Temperature ◽  
Charge Compensation ◽  
Spin Hamiltonian ◽  
Temperature Analysis ◽  
X Band ◽  
Superhyperfine Interaction ◽  
Hamiltonian Parameters ◽  
The Magnetic Field

Abstract A single crystal X-band EPR study of VO2+ and Cr3+ in Li2SO4 • H2O was carried out at room temperature. Analysis of the spectra indicates that VO2+ substitutes for Li+ and that there are two magnetically inequivalent Li+ sites. The charge compensation occurs by removal of a neighboring Li+ . The principal values of the g and A tensors of the spin Hamiltonian for the two sites were determined. Superhyperfine interaction of the 3d1 electron of VO2+ with the neighboring water protons in the unit cell was observed and found to be between 0 and 0.5 mT, depending on the orientation of the magnetic field. Two magnetically different sites were also observed for Cr3+ , and the results were explained by a rhombic spin Hamiltonian. The Hamiltonian parameters g, D, and E were determined. It is concluded that VO2+ and Cr3+ enter into the Li+ places and the charge is compensated by a Li+ vacancy in the VO2+ case and proton vacancies in the Cr3+ case.

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