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Observations of spontaneous breaking of the rotational symmetry in an electron fluid, the so-called "electronic nematicity," have been reported in several quantum materials. We have developed several different methods, based on angle-resolved transport measurements, to determine the amplitude and the director of the nematic order. We present methods that are applicable to thin films or single crystals, illustrate them with transport data obtained on copper oxide superconductors, and discuss their relative advantages and disadvantages. [ABSTRACT FROM AUTHOR]

The observation of nonzero voltage transverse to the current flow, in zero magnetic field, is a sensitive indication of the nematic order in cuprate superconductors. But this effect should be carefully identified and differentiated from various conceivable experimental artifacts. Here we discuss in detail the five types of artifacts commonly encountered in transport experiments and explain how we rule out these possibilities by decisive experimental evidence. [ABSTRACT FROM AUTHOR]

Recently, we have released the results of a comprehensive study of a couple thousand single-crystal La2−xSrxCuO4 films, covering densely the entire overdoped side of the phase diagram (Božović et al. Nature 536, 309-311, 2016; Wu et al. Nature 547, 432-435, 2017). Here, we review the key experimental findings, place them in the context of other important well-established facts and observations, and discuss their implications for our understanding of high-temperature superconductivity in cuprates. We conclude that it involves some new physics that requires going beyond the standard Fermi liquid description of the normal state and Bardeen-Cooper-Schrieffer description of the superconducting state. [ABSTRACT FROM AUTHOR]

We have synthesized LaSrCuO thin films using atomic layer-by-layer molecular beam epitaxy (ALL-MBE). The films are high-quality-singe crystal, atomically smooth, and very homogeneous. The critical temperature ( T ) shows a very little (<1 K) variation within a film of 10×10 mm area. The large statistics (over 2000 films) is crucial to discern intrinsic properties. In these films, we have measured the absolute value of the magnetic penetration depth λ with the accuracy better than 1 % and mapped densely the entire overdoped side of the LaSrCuO phase diagram. A new scaling law is established accurately for the dependence of T on the superfluid density. The scaling we observe is incompatible with the standard Bardeen-Cooper-Schrieffer picture and points to local pairing. [ABSTRACT FROM AUTHOR]

Since the discovery of high-temperature superconductivity in cuprates, proposals have been made that pairing may be local, in particular in underdoped samples. Here, we briefly review evidence for local pairs from our experiments on thin films of La Sr CuO , synthesized by atomic layer-by-layer molecular beam epitaxy (ALL-MBE). [ABSTRACT FROM AUTHOR]