Two-dimensional superconductivity at (110) LaAlO3/SrTiO3 interfaces

Han, Yu; Shen, Shengchun; You, Jinhong; Li, Haiou; Luo, Zhongzhong; Li, Cheng-Jian; Qu, Guo-Liang; Xiong, Chao; Dou, Rui-Fen; He, Lin; Naugle, D. G.; Guo, Guo-Ping; Nie, Jia-Cai

doi:10.1063/1.4901940

Cited by 50 publications

(44 citation statements)

References 46 publications

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“…We begin with the LaAlO 3 /SrTiO 3 heterostructures that show interface conductivity [36][37][38] for the three different orientations (001), (110), and (111) of the interface with respective point groups C 4v , C 2v , and C 3v while superconductivity has so far only been reported for the former two orientations. 1,5 Even though the proton number of Ti is smaller than that of the atoms relevant to the previously discussed materials, the experimentally reported strong spin-orbit splitting of the Fermi surfaces 39,40 shows that assumption (i) is clearly appropriate. From result (II), it follows that the condensates of the (001) and (110) interfaces must be necessarily time-reversal symmetric whereas the (111) heterostructure allows for exotic TRS-breaking superconductivity.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4][5] This is motivated by the promising role played by 2D superconductors in the search for topological Majorana modes and related applications, 6 by the tunability of the electronic properties, 2,4,[7][8][9] and by the fundamental interest in superconducting transitions in reduced dimensions. Particularly interesting examples are given by LaAlO 3 /SrTiO 3 heterostructures, that show very rich electronic behavior, 10 and single-layer FeSe on [001] SrTiO 3 with significantly enhanced transition temperatures compared to its bulk value.…”

Section: Introductionmentioning

confidence: 99%

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Selection rules for Cooper pairing in two-dimensional interfaces and sheets

2017

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Thin sheets deposited on a substrate and interfaces of correlated materials offer a plethora of routes towards the realization of exotic phases of matter. In these systems, inversion symmetry is broken which strongly affects the properties of possible instabilities -in particular in the superconducting channel. By combining symmetry and energetic arguments, we derive general and experimentally accessible selection rules for Cooper instabilities in noncentrosymmetric systems, which yield necessary and sufficient conditions for spontaneous time-reversal-symmetry breaking at the superconducting transition and constrain the orientation of the triplet vector. We discuss in detail the implications for various different materials. For instance, we conclude that the pairing state in thin layers of Sr 2 RuO 4 must, as opposed to its bulk superconducting state, preserve time-reversal symmetry with its triplet vector being parallel to the plane of the system. All triplet states of this system allowed by the selection rules are predicted to display topological Majorana modes at dislocations or at the edge of the system. Applying our results to the LaAlO 3 /SrTiO 3 heterostructures, we find that while the condensates of the (001) and (110) oriented interfaces must be time-reversal symmetric, spontaneous time-reversal-symmetry breaking can only occur for the less studied (111) interface. We also discuss the consequences for thin layers of URu 2 Si 2 and UPt 3 as well as for single-layer FeSe. On a more general level, our considerations might serve as a design principle in the search for time-reversal-symmetry-breaking superconductivity in the absence of external magnetic fields.npj Quantum Materials (2017) 2:9 ;

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Selection rules for Cooper pairing in two-dimensional interfaces and sheets

2017

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“…Recently, controlled growth on pseudo-cubic orientation LAO/STO(110) non-polarized interfaces has been successful and made the related investigations possible [13][14][15].…”

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confidence: 99%

Observation of quantum Griffiths singularity and ferromagnetism at the superconducting LaAlO3/SrTiO3(110) interface

et al. 2016

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Diverse phenomena emerge at the interface between band insulators LaAlO 3 and SrTiO 3 , such as superconductivity and ferromagnetism, showing an opportunity for potential applications as well as bringing fundamental research interests. Particularly, the two-dimensional electron gas formed at LaAlO 3 /SrTiO 3 interface offers an appealing platform for quantum phase transition from a superconductor to a weakly localized metal. Here we report the superconductor-metal transition in superconducting two-dimensional electron gas formed at LaAlO3/SrTiO3(110) interface driven by a perpendicular magnetic field. Interestingly, when approaching the quantum critical point, the dynamic critical exponent is not a constant but a diverging value, which is a direct evidence of quantum Griffiths singularity raised from quenched disorder at ultralow temperatures. Furthermore, the hysteretic property of magnetoresistance was firstly observed at LaAlO 3 /SrTiO 3 (110) interfaces, which suggests potential coexistence of superconductivity and ferromagnetism.

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“…Not restricted to merely the model system in the (001) direction, superconductivity is also shown in LaAlO 3 /SrTiO 3 interfaces along the (110) [47] and 111[48] direction.…”

Section: Superconductivitymentioning

confidence: 99%

Interfacial Phenomena in Atomically Engineered LaAlO3/SrTiO3 Heterostructures

Huijben¹

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This dissertation has been approved by the supervisors: prof. dr. ir. J.W.M. Hilgenkamp prof. dr. ir. A. Brinkman Voor Amy, Elena en Anita into quantum oscillations in LaAlO 3 /SrTiO 3 interfaces is evaluated. [In collaboration with the research group of prof. Zeitler, High Field Magnet Laboratory at Radboud University Nijmegen] In Chapter 5 the atomic intermixing between LaAlO 3 overlayer and SrTiO 3 substrate is studied in order to understand its relation with the doping mechanism. The result shows a vacancy-rich-site composition of neutrally charged Sr 1−1.5 La O layers, the formation of which already starts at the onset of deposition. The measured-site compositions do not take away the polar instability, which thus still requires a change from the nominal structure and/or composition at the-sites. Evidence is given for such a mechanism starting at a thickness of 3 unit cells. [In collaboration with the research group of prof. Stierle, Universität Hamburg, measurements performed at the ANKA Synchrotron Radiation Source at Karlsruhe Institute of Technology] In Chapter 6 LaAlO 3 /SrTiO 3 bilayers on SrTiO 3 substrates are studied in order to understand the coupling between subnanometer spaced conducting interfaces. This is achieved by scanning tunnelling microscopy (STM) and spectroscopy (STS) experiments on STO-capped LAO layers on STO(001) substrates, revealing the individual interface (2DEG) and surface (2DHG) conducting sheets including their temperature dependent coupling. [In collaboration with the research group of prof.

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Two-dimensional superconductivity at (110) LaAlO3/SrTiO3 interfaces

Cited by 50 publications

References 46 publications

Selection rules for Cooper pairing in two-dimensional interfaces and sheets

Selection rules for Cooper pairing in two-dimensional interfaces and sheets

Observation of quantum Griffiths singularity and ferromagnetism at the superconducting LaAlO3/SrTiO3(110) interface

Interfacial Phenomena in Atomically Engineered LaAlO3/SrTiO3 Heterostructures

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