Real Space Imaging of Spin Stripe Domain Fluctuations in a Complex Oxide

Longlong Wu, Yao Shen, Andi M. Barbour, Wei Wang, Dharmalingam Prabhakaran, Andrew T. Boothroyd, Claudio Mazzoli, John M. Tranquada, Mark P. M. Dean, and Ian K. Robinson

Phys. Rev. Lett. 127, 275301 – Published 28 December 2021

Abstract

Understanding the formation and dynamics of charge and spin-ordered states in low-dimensional transition metal oxide materials is crucial to understanding unconventional high-temperature superconductivity. ${La}_{2 - x} {Sr}_{x} {NiO}_{4 + δ}$ (LSNO) has attracted much attention due to its interesting spin dynamics. Recent x-ray photon correlation spectroscopy studies have revealed slow dynamics of the spin order (SO) stripes in LSNO. Here, we applied resonant soft x-ray ptychography to map the spatial distribution of the SO stripe domain inhomogeneity in real space. The reconstructed images show the SO domains are spatially anisotropic, in agreement with previous diffraction studies. For the SO stripe domains, it is found that the correlation lengths along different directions are strongly coupled in space. Surprisingly, fluctuations were observed in the real space amplitude signal, rather than the phase or position. We attribute the observed slow dynamics of the stripe domains in LSNO to thermal fluctuations of the SO domain boundaries.

Received 31 August 2021
Accepted 19 November 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.275301

Physics Subject Headings (PhySH)

Domain walls Dynamical phase transitions Magnetic anisotropy Magnetic domains Magnetic order Spin density waves

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Longlong Wu ^1,2,*, Yao Shen ¹, Andi M. Barbour³, Wei Wang ¹, Dharmalingam Prabhakaran⁴, Andrew T. Boothroyd⁴, Claudio Mazzoli³, John M. Tranquada ¹, Mark P. M. Dean ¹, and Ian K. Robinson ^1,5,†

¹Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
²Computational Science Initiative, Brookhaven National Laboratory, Upton, New York 11973, USA
³National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
⁴Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, United Kingdom
⁵London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom