scholarly journals Quantized and unquantized zero-bias tunneling conductance peaks in Majorana nanowires: Conductance below and above 2e2/h

2021 ◽  
Vol 103 (21) ◽  
Author(s):  
Haining Pan ◽  
Chun-Xiao Liu ◽  
Michael Wimmer ◽  
Sankar Das Sarma
Keyword(s):  
Tunneling Conductance ◽  
Zero Bias

scholarly journals Signature of a pair of Majorana zero modes in superconducting gold surface states

2020 ◽  
Vol 117 (16) ◽  
pp. 8775-8782 ◽  
Author(s):  
Sujit Manna ◽  
Peng Wei ◽  
Yingming Xie ◽  
Kam Tuen Law ◽  
Patrick A. Lee ◽  
...  
Keyword(s):  
Surface States ◽  
Gold Surface ◽  
Building Blocks ◽  
Energy Scale ◽  
Scanning Tunneling ◽  
Tunneling Conductance ◽  
Gold Nanowires ◽  
Noise Sources ◽  
Zero Bias ◽  
Zero Modes

Under certain conditions, a fermion in a superconductor can separate in space into two parts known as Majorana zero modes, which are immune to decoherence from local noise sources and are attractive building blocks for quantum computers. Promising experimental progress has been made to demonstrate Majorana zero modes in materials with strong spin–orbit coupling proximity coupled to superconductors. Here we report signatures of Majorana zero modes in a material platform utilizing the surface states of gold. Using scanning tunneling microscope to probe EuS islands grown on top of gold nanowires, we observe two well-separated zero-bias tunneling conductance peaks aligned along the direction of the applied magnetic field, as expected for a pair of Majorana zero modes. This platform has the advantage of having a robust energy scale and the possibility of realizing complex designs using lithographic methods.

Power Law Behavior of the Zero Bias Tunneling Conductance: the New Evidence for d -Wave Symmetry

2000 ◽  
Vol 17 (10) ◽  
pp. 760-761 ◽  
Author(s):  
Li Shao-Xiong ◽  
Tao Hong-Jie ◽  
Xuan Yi ◽  
Zhao Bai-Ru ◽  
Zhao Zhong-Xian
Keyword(s):  
Power Law ◽  
Tunneling Conductance ◽  
Zero Bias ◽  
Wave Symmetry ◽  
New Evidence ◽  
D Wave

TUNNELING IN A QUANTUM HALL EXCITONIC CONDENSATE

2002 ◽  
Vol 16 (20n22) ◽  
pp. 2923-2923 ◽  
Author(s):  
J. P. EISENSTEIN ◽  
I. B. SPIELMAN ◽  
L. N. PFEIFFER ◽  
K. W. WEST
Keyword(s):  
Ground State ◽  
Josephson Effect ◽  
Bose Condensate ◽  
Quantum Hall ◽  
Collective Modes ◽  
Tunneling Conductance ◽  
Electron Gases ◽  
Linear Dispersion ◽  
Zero Bias ◽  
Long Wavelength

Recent experiments on the tunneling conductance between parallel 2D electron gases at total Landau level filing ν tot = 1 are described. When the two layers are close enough together the ground state of the system may be viewed as a Bose condensate of excitons consisting of electrons in one layer paired with (conduction band) holes in the other. The measured tunneling conductance exhibits a spectacular resonance around zero bias which resembles the dc Josephson effect. This resonance is a signature of long wavelength Goldstone collective modes in the phase coherent ground state. Experiments performed with an added in-plane magnetic field have demonstrated the expected linear dispersion of this mode.

Nonlinear entangled quantum dynamics in many-body systems with strong electron correlation

2017 ◽  
Vol 31 (10) ◽  
pp. 1742009 ◽  
Author(s):  
Jongbae Hong
Keyword(s):  
Electron Correlation ◽  
Quantum Dynamics ◽  
Entangled State ◽  
Tunneling Conductance ◽  
Strong Electron Correlation ◽  
Strong Electron ◽  
Zero Bias ◽  
Highly Nonlinear ◽  
Quantum Impurity ◽  
Impurity System

A quantum impurity system out of equilibrium comprises two metallic reservoirs with different chemical potentials and one mediating spin impurity between them. We study the highly nonlinear tunneling conductance of this system, and clarify that three coherent peaks, one zero-bias peak and two side peaks, naturally appear in the tunneling conductance. We use the Liouvillian approach, in which a complete set of basis operators is available, and construct a Liouville matrix to obtain Green’s function at the mediating site. We show that the two coherent side peaks are the outcome of steady-state nonequilibrium combined with strong electron correlation at the mediating site. Tunneling in the quantum impurity system out of equilibrium is performed by an entangled state which is a linear combination of two Kondo singlets formed by the spin at the mediating site and the coherent spins in each reservoir. The fluctuation by incoherent spins is also included. The spectral weights and positions of the three coherent peaks are analytically discussed via atomic limit analysis. Our theoretical results well fit experimental data obtained for quantum point contacts with symmetric and asymmetric Kondo couplings.

scholarly journals A NOVEL MERON-INDUCED PSEUDOSPIN WAVE IN THE BILAYER QUANTUM HALL COHERENT STATE AND THE RESIDUAL ZERO-BIAS PEAK IN TUNNELING CONDUCTANCE

2003 ◽  
Vol 17 (26) ◽  
pp. 1377-1384
Author(s):  
YUE YU
Keyword(s):  
Coherent State ◽  
Bias Voltage ◽  
Rotational Symmetry ◽  
Quantum Hall ◽  
Tunneling Conductance ◽  
Zero Bias ◽  
Voltage Range ◽  
High Bias ◽  
Bilayer Quantum Hall ◽  
Periodic Domain Structure

In the bilayer quantum Hall coherent state for νT deviating slightly from unity, we show that, instead of the global order parameter, the periodic domain structure accompanying the charged meron pairs spontaneously breaks the pseudospin U(1) rotational symmetry. The motion of meron pairs induces a novel pseudospin wave. The long-range order of the periodic domains in a low bias voltage range leads to the residual zero-bias peak in the tunneling conductance, which can be distinct from the pseudopsin Goldstone feature in a high bias voltage range.

d-Wave Tunnel Junctions

1999 ◽  
Vol 13 (09n10) ◽  
pp. 1295-1299
Author(s):  
A. M. Cucolo ◽  
M. Cuoco ◽  
C. Noce
Keyword(s):  
Weak Coupling ◽  
Tunnel Junctions ◽  
Coupling Model ◽  
Normal Metal ◽  
Tunneling Conductance ◽  
Spin States ◽  
S Wave ◽  
Zero Bias ◽  
Zero Bias Conductance ◽  
D Wave

We study the tunneling spectra for superconductor-insulator-normal metal (S-I-N) tunnel junctions with an s -wave or a d -wave superconductor within the weak-coupling model. We deduce the temperature behavior of tunneling conductance and their peak positions as well as of the zero-bias conductance. The results obtained allow us to discriminate among the two singlet spin states.

scholarly journals Giant thermal spin-torque–assisted magnetic tunnel junction switching

2015 ◽  
Vol 112 (21) ◽  
pp. 6585-6590 ◽  
Author(s):  
Aakash Pushp ◽  
Timothy Phung ◽  
Charles Rettner ◽  
Brian P. Hughes ◽  
See-Hun Yang ◽  
...  
Keyword(s):  
Tunnel Junction ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Temperature Gradients ◽  
Large Temperature ◽  
Spin Torque ◽  
Tunneling Conductance ◽  
Zero Bias ◽  
Spin Polarized ◽  
Spin Torques

Spin-polarized charge currents induce magnetic tunnel junction (MTJ) switching by virtue of spin-transfer torque (STT). Recently, by taking advantage of the spin-dependent thermoelectric properties of magnetic materials, novel means of generating spin currents from temperature gradients, and their associated thermal-spin torques (TSTs), have been proposed, but so far these TSTs have not been large enough to influence MTJ switching. Here we demonstrate significant TSTs in MTJs by generating large temperature gradients across ultrathin MgO tunnel barriers that considerably affect the switching fields of the MTJ. We attribute the origin of the TST to an asymmetry of the tunneling conductance across the zero-bias voltage of the MTJ. Remarkably, we estimate through magneto-Seebeck voltage measurements that the charge currents that would be generated due to the temperature gradient would give rise to STT that is a thousand times too small to account for the changes in switching fields that we observe.

scholarly journals ZERO-BIAS CONDUCTANCE ANOMALY IN BILAYER QUANTUM HALL SYSTEMS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 2936-2939
Author(s):  
Y. N. JOGLEKAR ◽  
A. H. MACDONALD
Keyword(s):  
Filling Factor ◽  
Quantum Hall ◽  
Tunneling Conductance ◽  
Coulomb Interactions ◽  
Zero Bias ◽  
Rich Variety ◽  
Quantum Hall Systems ◽  
Zero Bias Conductance ◽  
Quantum Hall System ◽  
Bilayer Quantum Hall

Bilayer quantum Hall system at total filling factor ν=1 shows a rich variety of broken symmetry ground states because of the competition between the interlayer and intralayer Coulomb interactions. When the layers are sufficiently close, a bilayer system develops spontaneous interlayer phase-coherence that manifests itself through a spectacular enhancement of the zero-bias interlayer tunneling conductance. We present a theory of this tunneling conductance anomaly, and show that the zero-bias conductance is proportional to the square of the quasiparticle tunneling amplitude.

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