Physics Chat
Exploring the phase space of 3D Artificial Spin-ice systems
Speaker: Vani Lanka (Dr Sam Ladak's group)
Date: Thursday 9 February 2023
Time: 14:30
Venue: Queen's buildings North N3.23 with zoom live streaming
Artificial spin-ices (ASI) consist of periodically/aperiodically arranged nanomagnets on lattice sites moulded to various geometries. Extensive research upon frustration has shown limitations in 2D, therefore extending these systems into 3D gives rise for unconventional states of matter to be studied. In particular emergent magnetic monopoles, spin textures and dynamics. 3DASI follows local ordering principles, known as the ice rules, which aim to minimise magnetic charge. This research aims to develop energetically favourable 3DASI systems with extensively degenerate ground states, allowing artificial monopoles to move in a divergence-free vacuum. Two-photon lithography has allowed bulk spin ice geometries to be fabricated with high spatial resolution, potentially overcoming the limitations seen in 2D. By performing magnetic force microscopy (MFM) studies with the aid of micromagnetic simulations, magnetic monopole defects and transport within the lattice have been realised, revealing glimpses of charge ordered ground states. Monte Carlo simulations have demonstrated a rich phase diagram of ground states including various charge ordered states. Thus far our work has suggested that charge ordered ground states are achievable with regions of highly correlated magnetic charge. Our recent research aims to adjust lattice parameters, wire thickness/length and surface energetics to directly visualise the ground state. We model an annealing process using various demagnetising protocols. We also present future advances within exploration of the phase space via thermally active ASI aims to isolate magnetic monopoles. Dynamically, these systems open up a collection of technological applications through advancing memory, data storage and encryption. Overall, the field of artificial spin-ice has significant avenues to explore with exciting outcomes for the future.
References:
1. Williams, G., Hunt, M., Boehm, B. et al. Two-photon lithography for 3D magnetic nanostructure fabrication. Nano Res. 11, 845-854 (2018).
2. May, A., Hunt, M., Van Den Berg, A. et al. Realisation of a frustrated 3D magnetic nanowire lattice. Commun Phys 2, 13 (2019).
3. May, A., Saccone, M., van den Berg, A. et al. Magnetic charge propagation upon a 3D artificial spin-ice. Nat Commun 12, 3217 (2021).