${}^{139}$La NMR investigation in underdoped La${}_{1.93}$Sr${}_{0.07}$CuO${}_4$

Abstract

We report ${}^{139}$La and ${}^{63}$Cu nuclear magnetic and quadrupole resonance (NMR/NQR) studies in an underdoped La${}_{1.93}$Sr${}_{0.07}$CuO${}_4$ single crystal, focusing on the ${}^{139}$La NMR in the normal state. We demonstrate that the local structural distortions in the low-temperature orthorhombic structure cause the tilting of the direction of the electric field gradient (EFG) at the nuclei from the c axis, resulting in two NMR central transition spectra at both the ${}^{139}$La and ${}^{63}$Cu nuclei in an external field. Taking into account the tilt angle of the EFG, the temperature dependence of the ${}^{139}$La spectra allowed us to determine the ${}^{139}$La Knight shift and the structural order parameter. The angle and temperature dependence of the ${}^{139}$La spectrum is in perfect agreement with the macroscopic average structure and proves a displacive transition. The ${}^{139}$La nuclear spin-lattice relaxation rates, $T_1^{-1}$, suggest that La${}_{1.93}$Sr${}_{0.07}$CuO${}_4$ undergoes a gradual change to a temperature-independent paramagnetic regime in the high temperature region. Both the spectra and $T_1^{-1}$ of the ${}^{139}$La as a function of temperature reveal a sharp anomaly around $T_S=387(1)$ K, implying a first-order-like structural transition, and a dramatic change below ~70 K arising from collective glassy spin freezing.

arXiv comment7 pages, 7 figures, published in PRB

References in corpus (8)

• Lattice symmetry breaking in cuprate superconductors: Stripes, nematics, and superconductivity
• Inhomogeneous Low Frequency Spin Dynamics in La_{1.65}Eu_{0.2}Sr_{0.15}CuO_4
• Charge Segregation, Cluster Spin-Glass and Superconductivity in La1.94Sr0.06CuO4
• Glassy Spin Freezing and NMR Wipeout Effect in the High-T_c Superconductor La1.90Sr0.10CuO4: What is the Relationship With Stripes ?
• Incommensurate lattice distortion in the high temperature tetragonal phase of La${}_{2-x}$(Sr,Ba)${}_x$CuO${}_4$
• NMR Evidence for Charge Inhomogeneity in Stripe Ordered La_{1.8-x}Eu_{0.2}Sr_{x}CuO_4
• Advances in single crystal growth and annealing treatment of electron-doped HTSC
• The Local Structure of La1.65Eu0.2Sr 0.15CuO4 determined by 63Cu NMR Spectroscopy and Van Vleck Paramagnetism of Eu3+ Ions

Cited by in corpus (7)

• Neutron scattering study of spin ordering and stripe pinning in superconducting La${}_{1.93}$Sr${}_{0.07}$CuO${}_4$
• Unconventional short-range structural fluctuations in cuprate high-$T_c$ superconductors
• Competition between spin ordering and superconductivity near the pseudogap boundary in La2-xSrxCuO4: insights from NMR
• Magnetic field induced anisotropy of ${}^{139}\mathrm{La}$ spin-lattice relaxation rates in stripe ordered ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{CuO}}_4$
• Cu nuclear magnetic resonance study of charge and spin stripe order in La${}_{1.875}$Ba${}_{0.125}$CuO${}_4$
• Low-energy spin dynamics and critical hole concentrations in La${}_{2-x}$Sr${}_x$CuO${}_4$ ($0.07\le x\le 0.2$) revealed by ${}^{139}$La and ${}^{63}$Cu nuclear magnetic resonance
• Structural transitions in a doped lanthanum cuprate