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Free energy, Nuclear quadrupole resonance, Single crystals, Charge stripes, Charge-ordering, Lattice directions, Lows-temperatures, Ordering transitions, Spin order, Splittings, Stress studies, Tetragonal structure, Uniaxial stress, Temperature
Abstract:
We study the response of spin and charge order in single crystals of La1.875Ba0.125CuO4 to uniaxial stress through La139 nuclear magnetic resonance and Cu63 nuclear quadrupole resonance, respectively. In unstressed La1.875Ba0.125CuO4, the low-temperature tetragonal structure sets in below TLTT=57K, while the charge order and the spin order transition temperatures are TCO=54K and TSO=37K, respectively. We find that uniaxial stress along the [110] lattice direction strongly suppresses TCO and TSO, but has little effect on TLTT. In other words, under stress along [110] a large splitting (≈21K) opens between TCO and TLTT, showing that these transitions are not tightly linked. On the other hand, stress along [100] causes a slight suppression of TLTT but has essentially no effect on TCO and TSO. Magnetic field H along [110] stabilizes the spin order: the suppression of TSO under stress along [110] is slower under H∥[110] than H∥[001]. We develop a Landau free-energy model, and we interpret our findings as an interplay of symmetry-breaking terms driven by the orientation of spins. © 2023 American Physical Society.
