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Thermal and Quantum Phase Slips in Superconducting Nanowires
Published in Andrei D. Zaikin, Dmitry S. Golubev, Dissipative Quantum Mechanics of Nanostructures, 2019
Andrei D. Zaikin, Dmitry S. Golubev
To complete our brief overview, let us also mention about an experimental work [26, 326] on quantum tunneling of magnetic flux quanta demonstrating a coherent nature of QPS in superconducting nanowires and nanorings. We will return to this issue in the next chapter. Yet another experimental demonstration of quantum coherence of QPS is the observation of Coulomb blockade and Bloch oscillation features in Ti nanowires [266].
Properties of Quantum Transport
Published in Jian-Bai Xia, Duan-Yang Liu, Wei-Dong Sheng, Quantum Waveguide in Microcircuits, 2017
Jian-Bai Xia, Duan-Yang Liu, Wei-Dong Sheng
where Φ0 = h/e is the magnetic flux quantum. The electric current passing through the closed loop will oscillate periodically with the magnetic flux. When a current of10 mA passes through the loop, if there is a magnetic field of 0.02 TJ then the AB effect can result in distinct fluctuation.
Investigations of arsenic substitution on the physical, electrical and magnetic properties of Bi-2212 superconductors
Published in Phase Transitions, 2020
W. Labban, W. Malaeb, K. Habanjar, M.S. Hassan, R. Sakagami, Y. Kamihara, R. Awad
For the magnetism study, half magnetic-hysteresis loops are shown in Figure 5(a) and (b) up to 50 kOe field, at 5 and 30 K, respectively. Apparently, the magnitude of magnetization effectively depends on As content. It is obvious that sample As2 with 0.2 arsenic content has the largest hysteresis loop with the toughest diamagnetic behaviour at both applied temperatures. Thus, arsenic probably acts as an effective flux pinning centre in Bi-2212 superconductors. As the temperature increased, in Figure 5(b), a decrease in the area and in the maximum magnetization is observed. This is attributed to the decrease in the number of Cooper pairs as the temperature increases, as well as the motion of the pinning centres. This is a general characteristic feature of HTSC materials with granular structure and weak link between the grains. Moreover, at high field values, the separation vanishes as the upper and lower curves of the loops converge into a straight ‘irreversibility’ line. This line’s extrapolation intercepts with the x-axis at the temperature dependent upper critical field Hc2(T) (see the inset) [45]. These calculated values of Hc2, listed in Table 4, follow the same trend of Tc, with As1 having the highest Hc2. This is because the upper critical field is a superconducting parameter, which does not, unlike Jc, depend on the transport quality of the bulk. This can be remarked at the high field values, where the As2 line starts to approach the x-axis faster than the As1 line, as As1 possesses the highest Tc and hence the most stable superconducting state. The coherence length ξ values, listed in Table 4, were calculated using the Ginzburg-Landau theory by: where Φ0 is the magnetic flux quantum which has a value of 2.0678 × 10−15 T.m2 [46].