Zero-bias conductance vanishing induced by the same-spin-band Andreev reflection in half-metallic ferromagnet/superconductor contacts

2010 ◽  
Vol 81 (22) ◽  
Author(s):  
C. D. Feng ◽  
Zhi Ming Zheng ◽  
R. Shen ◽  
Baigeng Wang ◽  
D. Y. Xing
Keyword(s):  
Andreev Reflection ◽  
Zero Bias ◽  
Half Metallic ◽  
Zero Bias Conductance ◽  
Metallic Ferromagnet

scholarly journals FIRST-PRINCIPLES CALCULATIONS OF SPIN-TRIPLET ANDREEV REFLECTION SPECTRA AT HALF-METALLIC FERROMAGNET/SUPERCONDUCTOR INTERFACE

2012 ◽  
Vol 26 (31) ◽  
pp. 1250205 ◽  
Author(s):  
LING TANG
Keyword(s):  
First Principles ◽  
Andreev Reflection ◽  
Magnetic Moments ◽  
S Wave ◽  
Interfacial Roughness ◽  
Zero Bias ◽  
Half Metallic ◽  
Magnetic Disorder ◽  
Spin Triplet ◽  
Metallic Ferromagnet

Combining the first-principles noncollinear calculations of scattering matrices with Andreev approximation, we investigated the spin-triplet Andreev reflection (AR) spectra for the interface between half-metallic ferromagnet Co 2 MnSi and s-wave BCS superconductor Al with and without interfacial roughness, where the orientations of magnetic moments near the interface are randomly distributed. The calculated results show that the AR spectra have peak structures near zero bias for the clean interface with relative weak magnetic disorder. With the increasing degree of interfacial roughness or magnetic disorder, these subgap peaks of conductance spectra will be washed out. The results also show that the value of subgap conductance spectrum can be raised significantly by the magnetic disorder. Finally, our calculations reveal that the long-range spin-triplet AR in Co 2 MnSi / Al (001) interface can be enhanced by a small amount of interfacial roughness.

scholarly journals Point-contact Andreev reflection spectroscopy on Bi2Se3 single crystals

2016 ◽  
Vol 30 (13) ◽  
pp. 1642002 ◽  
Author(s):  
C. R. Granstrom ◽  
I. Fridman ◽  
H.-C. Lei ◽  
C. Petrovic ◽  
J. Y. T. Wei
Keyword(s):  
Single Crystals ◽  
Andreev Reflection ◽  
Surface Condition ◽  
Three Dimensional ◽  
Point Contact ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Zero Bias ◽  
Zero Bias Conductance

To study how Andreev reflection (AR) occurs between a superconductor and a three-dimensional topological insulator (TI), we use superconducting Nb tips to perform point-contact AR spectroscopy at 4.2 K on as-grown single crystals of Bi2Se3. Scanning tunneling spectroscopy and scanning tunneling microscopy are also used to characterize the superconducting tip and both the doping level and surface condition of the TI sample. The point-contact measurements show clear spectral signatures of AR, as well as a depression of zero-bias conductance with decreasing junction impedance. The latter observation can be attributed to interfacial Rashba spin-orbit coupling, and the presence of bulk bands at the Fermi level in our samples suggests that bulk states of Bi2Se3 are involved in the observed AR.

Zero Bias Conductance Peak in HTS above Critical Temperature

2003 ◽  
Vol 17 (10n12) ◽  
pp. 505-518
Author(s):  
P. Mikheenko ◽  
R. Chakalov ◽  
R. I. Chakalova ◽  
M. S. Colclough ◽  
C. M. Muirhead
Keyword(s):  
Critical Temperature ◽  
Theoretical Prediction ◽  
Room Temperature ◽  
Andreev Reflection ◽  
Zero Bias ◽  
Conductance Peak ◽  
Extensive Search ◽  
Sample Heating ◽  
Ybco Sample ◽  
Zero Bias Conductance

It has recently been proposed that if phase incoherent preformed pairs exist above critical temperature (Tc), Andreev reflection should be observable above Tc too. A distinctive feature of Andreev reflection is a zero bias conductance peak (ZBCP) in the conductance/voltage (G/V) characteristics. We have performed an extensive search for the ZBCP in HTS/normal-metal planar junctions including samples which have been annealed in Argon in an attempt to induce underdoping and enhancement of the pseudogap temperature. We have observed a maximum in the G/V characteristics above Tc in a number of samples and contact configurations. In some samples this behavior persists up to room temperature, but has a very broad voltage scale, much greater than the gap voltage. In YBa 2 Cu 3 O x/ Au and YBa 2 Cu 3 O x/ Ag contacts the form and amplitude of the ZBCP is close to the theoretical prediction, but the origin of this effect could also be in sample heating. One particularly curious result comes from an Au/LSMO/YBCO sample that shows a clear sub-gap ZBCP over the temperature range 15–266 K.

scholarly journals Anomalous Zero-Bias Conductance Peak in a Nb–InSb Nanowire–Nb Hybrid Device

Nano Letters ◽  
2012 ◽  
Vol 12 (12) ◽  
pp. 6414-6419 ◽  
Author(s):  
M. T. Deng ◽  
C. L. Yu ◽  
G. Y. Huang ◽  
M. Larsson ◽  
P. Caroff ◽  
...  
Keyword(s):  
Zero Bias ◽  
Hybrid Device ◽  
Conductance Peak ◽  
Zero Bias Conductance

Study of Co2MnAl Heusler alloy as half metallic ferromagnet

2010 ◽  
Vol 84 (6) ◽  
pp. 717-721 ◽  
Author(s):  
Dibya Prakash Rai ◽  
Javad Hashemifar ◽  
Morteeza Jamal ◽  
Lalmuanpuia ◽  
M. P. Ghimire ◽  
...  
Keyword(s):  
Heusler Alloy ◽  
Half Metallic ◽  
Metallic Ferromagnet

The effect of lanthanide impurities on the physical properties of half-metallic ferromagnet Co2MnSi

2008 ◽  
Vol 255 (3) ◽  
pp. 685-687 ◽  
Author(s):  
R. Tetean ◽  
L. Chioncel ◽  
E. Burzo ◽  
N. Bucur ◽  
A. Bezergheanu ◽  
...  
Keyword(s):  
Physical Properties ◽  
Half Metallic ◽  
Metallic Ferromagnet

scholarly journals Spin Gapless Semiconductor–Nonmagnetic Semiconductor Transitions in Fe-Doped Ti2CoSi: First-Principle Calculations

2018 ◽  
Vol 8 (11) ◽  
pp. 2200 ◽  
Author(s):  
Yu Feng ◽  
Zhou Cui ◽  
Ming-sheng Wei ◽  
Bo Wu ◽  
Sikander Azam
Keyword(s):  
Magnetic Moment ◽  
Electronic Structures ◽  
Magnetic Moments ◽  
Total Magnetic Moment ◽  
First Principle ◽  
Half Metallic ◽  
Heusler Compound ◽  
First Principle Calculations ◽  
Metallic Ferromagnet

Employing first-principle calculations, we investigated the influence of the impurity, Fe atom, on magnetism and electronic structures of Heusler compound Ti2CoSi, which is a spin gapless semiconductor (SGS). When the impurity, Fe atom, intervened, Ti2CoSi lost its SGS property. As TiA atoms (which locate at (0, 0, 0) site) are completely occupied by Fe, the compound converts to half-metallic ferromagnet (HMF) TiFeCoSi. During this SGS→HMF transition, the total magnetic moment linearly decreases as Fe concentration increases, following the Slate–Pauling rule well. When all Co atoms are substituted by Fe, the compound converts to nonmagnetic semiconductor Fe2TiSi. During this HMF→nonmagnetic semiconductor transition, when Fe concentration y ranges from y = 0.125 to y = 0.625, the magnetic moment of Fe atom is positive and linearly decreases, while those of impurity Fe and TiB (which locate at (0.25, 0.25, 0.25) site) are negative and linearly increase. When the impurity Fe concentration reaches up to y = 1, the magnetic moments of Ti, Fe, and Si return to zero, and the compound is a nonmagnetic semiconductor.

scholarly journals Origin of bias-independent conductance plateaus and zero-bias conductance peaks in Bi2Se3/NbSe2 hybrid structures

2017 ◽  
Vol 96 (7) ◽  
Author(s):  
Hui Li ◽  
Tong Zhou ◽  
Jun He ◽  
Huan-Wen Wang ◽  
Huachen Zhang ◽  
...  
Keyword(s):  
Hybrid Structures ◽  
Zero Bias ◽  
Zero Bias Conductance
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