Test for nonreciprocal circular birefringence inYBa2Cu3

Abstract

We have measured the amount of nonreciprocal circular birefringence of 50 to 800 A YBa2Cu3C>7 films in transmission with a 15-j/m beam diameter. A novel instrument with a sensitivity of 2 //rad for nonreciprocal phase shifts was developed by modifying a fiber-optic gyroscope. It is insensitive to reciprocal phase shifts. We observed no nonreciprocal phase shifts in any samples.PACS numbers: 74.65.+nOne of the most exciting proposals for the theory of the cuprate high-temperature superconductors (HTSC) is the so-called "anyon superconductivity." 1 " 3 This theory is based on the concept that in two spatial dimensions, one can obtain not only quantum ideal Bose and Fermi gases, but also quantum ideal gases of new types of particles that interpolate between those two extremes, and hence obey fractional statistics. Those particles are known generically as anyons. It was first pointed out by Laughlin and co-workers 4~6 that these gases form superfluids, and become superconductors if the anyons are electrically charged. A striking property of such a superconductor is that its ground state exhibits violation of parity (P) and time-reversal (T) symmetries. 3 Similar to a magnetic material, an anyon superconductor will exhibit a spontaneous Hall effect and magneto-optical effects. If the cuprates are indeed anyon superconductors then in a transmission experiment through a thin HTSC film, one expects to observe a nonreciprocal rotation of polarization equivalent to the Faraday effect. In reflection, one expects to see an effect resembling the polar Kerr effect. Both effects are nonreciprocal as a consequence of the breakdown of time-reversal symmetry. 1 ' 3In a recent experiment, Lyons et al. 1 reported such nonreciprocal optical effects in reflection from various HTSC. They constructed an optical system to measure the circular dichroism </> which is related to the reflectivity for right and left circularly polarized light by R± ^Re-*.Since one expects the anyon material to break into domains, the averaged nonreciprocal optical effect will be zero. The distribution width a of the values of </> is related to the circular dichroism of a single domain 0o by o~-<t>od/s, where d is the domain size and s is the beam size. Lyon et al. reported a nonzero value for a that increased from the noise level ( -25 /irad) at 300 K to -250 //rad as the temperature was lowered.In this paper we present data taken on high-quality YBa2Cu3<>7 (YBCO) films which indicate no measurable nonreciprocal effect. Using a modified fiber gyroscope we have been able to measure nonreciprocal phase shifts with high sensitivity while simultaneously rejecting all reciprocal effects. The phase shift we measure is AQ> sss 27rl(n + -n-)/X, where n+ and n-are the indices of refraction for circularly polarized light of the same handedness propagating in opposite directions through the sample. Equivalently /*+ and n-could refer to the two circular components of a single beam of linearly polarized light, in which case AO is related to the Faraday rotation angle 0 by...

Singular or non-Fermi liquids

“…This state is superconducting. The predicted time-reversal broken properties have not been observed experimentally [248].…”

Instability of the non-Fermi-liquid state of the Sachdev-Ye-Kitaev model

“…Spontaneous time-reversal symmetry breaking in experimental systems can be probed through Kerr rotation, which has been successfully applied to various condensed matter systems [39][40][41][42] . Similar perturbations (with an opposite sign) can drive the SYK q model with q > 4 to a series of fixed points with continuously varying scaling dimensions.…”

Planar metamaterial with transmission and reflection that depend on the direction of incidence

“…It is curious to note that the observed effect of circular differential reflection has a striking resemblance with reflective circular dichroism of anisotropic high-temperature superconductors 11,12 that was investigated in search for anyons ͑fractional statistic quasi-particles and agents of superconductivity that simultaneously violate time reversal and parity symmetry͒ and still remains a topic of intensive research. 13 In conclusion, we have demonstrated strong resonant directional and polarization asymmetry of normal incidence reflection and transmission of circularly polarized light from and through a planar chiral metamaterial.…”