Three-Axis Vector Nano Superconducting Quantum Interference Device

TL;DR

This paper introduces a three-axis nanoSQUID device capable of measuring the three components of magnetic moments in individual nanoparticles with high sensitivity at cryogenic temperatures.

Contribution

It presents the design, fabrication, and performance evaluation of a novel three-axis vector nanoSQUID based on Nb/HfTi/Nb Josephson junctions, enabling tridimensional magnetic measurements.

Findings

Achieved flux noise below 250 nΦ₀/√Hz

Demonstrated operation at 4.2 K and magnetic fields up to 50 mT

Estimated spin sensitivities of 630 μ_B/√Hz and 70 μ_B/√Hz for different components

Abstract

We present the design, realization and performance of a three-axis vector nano Superconducting QUantum Interference Device (nanoSQUID). It consists of three mutually orthogonal SQUID nanoloops that allow distinguishing the three components of the vector magnetic moment of individual nanoparticles placed at a specific position. The device is based on Nb/HfTi/Nb Josephson junctions and exhibits linewidths of $\sim 250$ nm and inner loop areas of $600 \times 90$ nm$^2$ and $500 \times 500$ nm$^2$. Operation at temperature $T=4.2$ K, under external magnetic fields up to $\sim 50$ mT is demonstrated. The experimental flux noise below $\sim 250$ ${\rm n}\Phi_0/\sqrt{\rm Hz}$ in the white noise limit and the reduced dimensions lead to a total calculated spin sensitivity of $\sim 630$ $\mu_{\rm B}/\sqrt{\rm Hz}$ and $\sim 70$ $\mu_{\rm B}/\sqrt{\rm Hz}$ for the in-plane and out-of-plane components of the vector magnetic moment, respectively. The potential of the device for studying tridimensional properties of individual nanomagnets is discussed.