Spin-like susceptibility of metallic and insulating thin films at low temperature

Abstract

Susceptibility measurements of patterned thin films at sub-K temperatures were carried out using a scanning SQUID microscope that can resolve signals corresponding to a few hundred Bohr magnetons. Several metallic and insulating thin films, even oxide-free Au films, show a paramagnetic response with a temperature dependence that indicates unpaired spins as the origin. The observed response exhibits a measurable out-of-phase component, which implies that these spins will create 1/f-like magnetic noise. The measured spin density is consistent with recent explanations of low frequency flux noise in SQUIDs and superconducting qubits in terms of spin fluctuations, and suggests that such unexpected spins may be even more ubiquitous than already indicated by earlier measurements. Our measurements set several constraints on the nature of these spins.

arXiv commentJournal version. 4 pages, 2 figures. See http://www.stanford.edu/group/moler/publications.html for the auxiliary document containing additional data and discussion (Ref. 15). Changes w.r.t. v1: Clarified some details, moved some technical points to auxiliary document

References in corpus (15)

• Decoherence of flux qubits due to 1/f flux noise
• Persistent currents in normal metal rings
• Dephasing of Electrons in Mesoscopic Metal Wires
• Model for l/f Flux Noise in SQUIDs and Qubits
• 1/f Flux Noise in Josephson Phase Qubits
• Interaction effects and phase relaxation in disordered systems
• Magnetism in SQUIDs at Millikelvin Temperatures
• Microscopic origin of low frequency flux noise in Josephson circuits
• Dangling-bond spin relaxation and magnetic 1/f noise from the amorphous-semiconductor/oxide interface: Theory
• Magnetic field enhancement of superconductivity in ultra-narrow wires
• Probing Noise in Flux Qubits via Macroscopic Resonant Tunneling
• Electrical activation and electron spin coherence of ultra low dose antimony implants in silicon
• Geometrical dependence of low frequency noise in superconducting flux qubits
• Enhancing superconductivity: Magnetic impurities and their quenching by magnetic fields
• Strong magnetic scattering from TiO${}_x$ adhesion layers

Cited by in corpus (38)

• Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface
• 1/f noise: implications for solid-state quantum information
• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• Probing surface noise with depth-calibrated spins in diamond
• On the surface paramagnetism of diamond
• Fundamental studies of superconductors using scanning magnetic imaging
• Diamond surface engineering for molecular sensing with nitrogen-vacancy centers
• Localization of Metal-Induced Gap States at the Metal-Insulator Interface:Origin of Flux Noise in SQUIDs and Superconducting Qubits
• Flux qubit noise spectroscopy using Rabi oscillations under strong driving conditions
• Scanning SQUID Susceptometry of a paramagnetic superconductor
• Candidate source of flux noise in SQUIDs: adsorbed oxygen molecules
• Magnetic Resonance Force Microscopy of paramagnetic electron spins at millikelvin temperatures
• Scanning gradiometry with a single spin quantum magnetometer
• NanoSQUIDs: Basics & recent advances
• Pure dephasing in flux qubits due to flux noise with spectral density scaling as $1/f^{\alpha }$
• Extending the Quantum Coherence of a Near-Surface Qubit by Coherently Driving the Paramagnetic Surface Environment
• Quantitative evaluation of defect-models in superconducting phase qubits
• Noise correlations in a flux qubit with tunable tunnel coupling
• Correlated flux noise and decoherence in two inductively coupled flux qubits
• Mott transition in granular aluminum
• Electric noise spectra of a near-surface nitrogen vacancy center diamond with a protective layer
• Flux $1/f^{\alpha }$ noise in 2D Heisenberg spin glasses: effects of weak anisotropic interactions
• Hydrogen as a Source of Flux Noise in SQUIDs
• Observation of Co-tunneling in Pairs of Coupled Flux Qubits
• Surface roughness noise analysis and comprehensive noise effects on depth-dependent coherence time of NV centers in diamond
• Nonequilibrium Spin Noise and Noise of Susceptibility
• Modeling Flux Noise in SQUIDs Due to Hyperfine Interactions
• Dissipationless dynamics of randomly coupled spins at high temperatures
• 1/f Noise from the Laws of Thermodynamics for Finite-Size Fluctuations
• Noise and microresonance of critical current in Josephson junction induced by Kondo trap states
• An Ising-Glauber Spin Cluster Model for Temperature Dependent Magnetization Noise in SQUIDs
• Efect of magnetic Gd impurities on superconductivity in MoGe films with different thickness and morphology
• 1/f noise in quantum nanoscience
• 1/f Flux Noise in low-T${}_c$ SQUIDs due to Superparamagnetic Phase Transitions in Defect Clusters
• Kubo spins in nano-scale aluminum grains: A muon spin relaxation study
• Enhanced superconductivity, Kondo behavior and negative-curvature resistivity of oxygen-irradiated thin films of aluminium
• Design concepts for an improved integrated scanning SQUID
• Temperature dependent diamagnetic-paramagnetic transitions in metal/semiconductor quantum rings