Magnetic inhomogeneity in charge-ordered <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>1.885</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mrow><mml:mn>0.115</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>CuO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math> studied by NMR
A. Larry Arsenault, Takashi Imai, Philip M. Singer, Kenji Suzuki, M. Fujita
Abstract
We report the inverse Laplace transform analysis of the $^{139}\mathrm{La}$ nuclear spin-lattice relaxation rate $1/{T}_{1}$ (${\mathrm{ILTT}}_{1}$ analysis) in charge-ordered ${\mathrm{La}}_{1.885}{\mathrm{Sr}}_{0.115}{\mathrm{CuO}}_{4}$ (${T}_{\mathrm{charge}}\ensuremath{\simeq}80$ K, ${T}_{c}\ensuremath{\simeq}{T}_{\mathrm{spin}}^{\mathrm{neutron}}=30$ K), and shed light on its magnetic inhomogeneity. We deduce the probability density function $P(1/{T}_{1})$ of the distributed $1/{T}_{1}$ (i.e., the histogram of distributed $1/{T}_{1}$) by taking the inverse Laplace transform of the experimentally observed nuclear magnetization recovery curve $M(t)$. We demonstrate that spin freezing sets in in some domains precisely below the onset of charge order at ${T}_{\mathrm{charge}}$, but their volume fraction grows only gradually toward ${T}_{c}$. Nearly a half of the sample volume exhibits properties expected for canonical high-${T}_{c}$ cuprates without charge order even near ${T}_{c}$. Our findings explain why charge order does not suppress ${T}_{c}$ of ${\mathrm{La}}_{1.885}{\mathrm{Sr}}_{0.115}{\mathrm{CuO}}_{4}$ as significantly as in ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{CuO}}_{4}$.