paper

$^{139}$ La NMR investigation of the interplay between the lattice, charge, and spin dynamics in charge ordered high $T_{c}$ cuprate La $_{1.875}$ Ba $_{0.125}$ CuO $_{4}$

arXiv:2203.04265 · doi:10.1103/PhysRevB.101.174508

Abstract

We investigate the interplay between the lattice, charge, and spin dynamics in charge ordered high $T_{c}$ cuprate La $_{1.875}$ Ba $_{0.125}$ CuO $_{4}$ ( $T_{c} = 4$ ~K) based on the inverse Laplace transform (ILT) analysis of the $^{139}$ La nuclear spin-lattice relaxation rate $1/ T_{1}$ (dubbed ILTT $_{1}$ analysis here after). A major thrust of the ILTT $_{1}$ analysis is that one can deduce the probability density function $P (1/ T_{1})$ of distributed $1/ T_{1}$ . We demonstrate that $1/ T_{1}^{l m}$ , defined as the log-mean (i.e. the center of gravity on a logarithmic scale) of $P (1/ T_{1})$ , can be well approximated by $1/ T_{1}^{s t r}$ deduced from the phenomenological stretched fit, however, $P (1/ T_{1})$ can provide much richer insight into how the lattice, charge, and spin fluctuations and their distribution develop near and below the long range charge order at $T_{c ha r g e} \sim 54$ ~K. Upon entering the charge ordered state, a divergent increase of $1/ T_{1}^{l m}$ toward the spin ordering at $T_{s p in}^{I^¼ S R} ≃ 35$ ~K is accompanied by an asymmetric broadening of $P (1/ T_{1})$ . Even deep inside the charge ordered state, $1/ T_{1}$ at a gradually diminishing fraction of $^{139}$ La sites continues to slow down as temperature is lowered, as expected for canonical superconducting CuO $_{2}$ planes without enhanced spin fluctuations. The fraction of such canonical $^{139}$ La sites almost disappears by $≃ 40$ ~K. In contrast, nearly a half of the $^{139}$ La sites in La $_{1.885}$ Sr $_{0.115}$ CuO $_{4}$ ( $T_{c ha r g e} ≃ 80$ ~K) still exhibits the canonical behavior without enhanced spin fluctuations even near its $T_{c} = 31$ ~K. These contrasting behaviors explain why superconductivity in La $_{1.875}$ Ba $_{0.125}$ CuO $_{4}$ is more strongly suppressed than in La $_{1.885}$ Sr $_{0.115}$ CuO $_{4}$ despite the lower onset temperature of the charge order.

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139La NMR investigation of the interplay between the lattice, charge, and spin dynamics in charge ordered high Tc​ cuprate La1.875​Ba0.125​CuO4​

Abstract

$^{139}$ La NMR investigation of the interplay between the lattice, charge, and spin dynamics in charge ordered high $T_{c}$ cuprate La $_{1.875}$ Ba $_{0.125}$ CuO $_{4}$