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I present new measurements of resistivity, Hall Effect, magnetoresistance (MR) and thermopower in the electron-doped cuprate La_2-xCe_xCuO₄ for 0.19≥ x ≥0.08 as a function of temperature and magnetic field. The surprising results are:
1) The normal state MR has an anomalous linear-in-H behavior [1] at the same doping (0.14 to 0.175) where a linear-in-T resistivity was previously observed for H>H_c2 [2]. Beyond the SC dome (x > 0.175) conventional metallic behavior is found.
2) The normal state Seebeck coefficient, S/T, exhibits a low temperature –lnT dependence at the same dopings [3]. Conventional S/T = constant metallic behavior is found for x >0.175.
3) Itinerant ferromagnetism is found below 4K for doping beyond the SC dome [4].
I conclude that conventional Fermi liquid theory cannot explain (1) and (2). Moreover, the magnitude of the anomalous magnetoresistance and thermopower scales with Tc, suggesting that the origin of the superconductivity is correlated with the anomalous normal state properties.
1.T. Sarkar et al., Sci. Adv. 5, eaav6753 (2019).
2.K. Jin et al. , Nature 476, 73 (2011).
3.P. R. Mandal et al., PNAS 116, 5991(2019).
4.T. Sarkar et al., arXiv:1902.11235.