Film-thickness-driven superconductor to insulator transition in cuprate superconductors

Jang, Heesuk; Lim, Ji Soo; Yang, Chan−Ho

doi:10.1038/s41598-020-60037-y

Cited by 15 publications

(10 citation statements)

References 47 publications

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“…Reduction in thickness introduces more disorder 14 , 40 – 42 as that is also evident in the increased R n presented in Figs. 1 b and 2 d. However, relating disorder directly to the resistivity would not be appropriate in the present scenario as there are secondary phases present along with TiN.…”

Section: Resultsmentioning

confidence: 65%

A robust nitridation technique for fabrication of disordered superconducting TiN thin films featuring phase slip events

Yadav¹,

Kaushik²,

Saravanan³

et al. 2021

Sci Rep

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Disorder induced phase slip (PS) events appearing in the current voltage characteristics (IVCs) are reported for two-dimensional TiN thin films produced by a robust substrate mediated nitridation technique. Here, high temperature annealing of Ti/Si3N4 based metal/substrate assembly is the key to produce majority phase TiN accompanied by TiSi2 & elemental Si as minority phases. The method itself introduces different level of disorder intrinsically by tuning the amount of the non-superconducting minority phases that are controlled by annealing temperature (Ta) and the film thickness. The superconducting critical temperature (Tc) strongly depends on Ta and the maximum Tc obtained from the demonstrated technique is about 4.8 K for the thickness range ~ 12 nm and above. Besides, the dynamics of IVCs get modulated by the appearance of intermediated resistive steps for decreased Ta and the steps get more prominent for reduced thickness. Further, the deviation in the temperature dependent critical current (Ic) from the Ginzburg–Landau theoretical limit varies strongly with the thickness. Finally, the Tc, intermediate resistive steps in the IVCs and the depairing current are observed to alter in a similar fashion with Ta and the thickness indicating the robustness of the synthesis process to fabricate disordered nitride-based superconductor.

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Section: Resultsmentioning

confidence: 65%

A robust nitridation technique for fabrication of disordered superconducting TiN thin films featuring phase slip events

Yadav¹,

Kaushik²,

Saravanan³

et al. 2021

Sci Rep

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show abstract

“…Generally, WL and EEI play major roles for the appearance of resistance peak and upturn in R(T) for twodimensional homogeneously disordered materials [4,8,25,26]. However, the dimensionality of the system is very much sensitive to WL & EEI and superconducting fluctuations, therefore characteristic length scales such as the superconducting coherence length 𝜉 𝐺𝐿 (0…”

Section: Resultsmentioning

confidence: 99%

Probing electron-electron interaction along with superconducting fluctuations in disordered TiN thin films

Yadav

Kaushik²,

Saravanan³

et al. 2023

Phys. Rev. B

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In 2D disordered superconductors prior to superconducting transition, the appearance of a resistance peak in the temperature dependent resistance [R(T)] measurements indicates the presence of weak localization (WL) & electron-electron interaction (EEI) in diffusion channel and superconducting fluctuations in the Cooper channel. Here, we demonstrate an interplay between superconducting fluctuations and electronelectron interaction by low temperature magnetotransport measurements for a set of 2D disordered TiN thin films. While cooling down the sample, a characteristic temperature T* is obtained from the R(T) at which superconducting fluctuations start to appear. The upturn in R(T) above T* corresponds to WL and/or EEI. By the temperature and field dependences of the observed resistance, we show that the upturn in R(T) originates mainly from EEI with a negligible contribution from WL. Further, we have used the modified Larkin's electron-electron attraction strength β(T/Tc), containing a field induced pair breaking parameter, in the Maki-Thompson (MT) superconducting fluctuation term. Here, the temperature dependence of the β(T/Tc) obtained from the magnetoresistance analysis shows a diverging behavior close to Tc and it remains almost constant at higher temperature within the limit of ln(T/Tc) <1. Interestingly, the variation of β(T/Tc) on the reduced temperature (T/Tc) offers a common trend which has been closely followed by all the concerned samples presented in this study. Finally, the temperature dependence of inverse phase scattering time (𝜏 𝜙 −1 ), as obtained from the magnetoresistance analysis, clearly shows two different regimes; the first one close to Tc follows the Ginzburg-Landau relaxation rate (𝜏 𝐺𝐿 −1 ), whereas, the second one at high temperature varies almost linearly with temperature indicating the dominance of inelastic electron-electron scattering for the dephasing mechanism. These two regimes are followed in a generic way by all the samples in spite of being grown under different growth conditions.

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“…Results of the XRD and RHEED analyses reveal LBCO belonging to the I4/mmm phase 25 – 27 (see Supplementary Table 1 for details). It is noted that the c -axis lattice parameter of the LBCO film is revealed to be about 13.32 Å, which is typical for overdoped cuprates 28 – 31 . Collectively, these results suggest that epitaxial growth of LBCO film onto LAO(001) substrate has been realized with the following relationship given by {LBCO(001)//LAO(001) and LBCO < 001 > //LAO < 001 > }.…”

Section: Resultsmentioning

confidence: 91%

“…Prior to each deposition stage, the LBCO and Au targets are pre-ablated at 10 Hz with 2000 pulses. Transport measurement suggests that LBCO/LAO films with thicknesses of up to 12uc are in the regime of insulator-metal transition as a function of temperature and thickness 30 , 31 .…”

Section: Methodsmentioning

confidence: 99%

Anomalous Ferromagnetism of quasiparticle doped holes in cuprate heterostructures revealed using resonant soft X-ray magnetic scattering

et al. 2022

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We report strong ferromagnetism of quasiparticle doped holes both within the ab-plane and along the c-axis of Cu-O planes in low-dimensional Au/d-La1.8Ba0.2CuO4/LaAlO3(001) heterostructures (d = 4, 8 and 12 unit-cells) using resonant soft X-ray and magnetic scattering together with X-ray magnetic circular dichroism. Interestingly, ferromagnetism is stronger at a hole doped peak and at an upper Hubbard band of O with spin-polarization degree as high as 40%, revealing strong ferromagnetism of Mottness. For in-ab-plane spin-polarizations, the spin of doped holes in O2p–Cu3d–O2p is a triplet state yielding strong ferromagnetism. For out-of-ab-plane spin-polarization, while the spins of doped holes in both O2p–O2p and Cu3d–Cu3d are triplet states, the spin of doped holes in Cu3d–O2p is a singlet state yielding ferrimagnetism. A ferromagnetic-(002) Bragg-peak of the doped holes is observed and enhanced as a function of d revealing strong ferromagnetism coupling between Cu-O layers along the c-axis.

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Film-thickness-driven superconductor to insulator transition in cuprate superconductors

Cited by 15 publications

References 47 publications

A robust nitridation technique for fabrication of disordered superconducting TiN thin films featuring phase slip events

A robust nitridation technique for fabrication of disordered superconducting TiN thin films featuring phase slip events

Probing electron-electron interaction along with superconducting fluctuations in disordered TiN thin films

Anomalous Ferromagnetism of quasiparticle doped holes in cuprate heterostructures revealed using resonant soft X-ray magnetic scattering

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