Nuclear magnetic resonance force microscopy with a microwire rf source

TL;DR

This paper demonstrates a highly localized and efficient nuclear magnetic resonance force microscopy technique using a microwire rf source, achieving strong rf fields and long spin lifetimes at cryogenic temperatures.

Contribution

It introduces a novel microwire rf source integrated with a nanomagnetic tip for enhanced MRFM measurements with high field gradients and low power dissipation.

Findings

Achieved rf magnetic fields over 4 mT at 115 MHz within 100 nm of the source.

Produced field gradients greater than 10^5 T/m with an integrated FeCo tip.

Demonstrated long spin lifetimes of up to 15 seconds at 4 K.

Abstract

We use a 1.0-um-wide patterned Cu wire with an integrated nanomagnetic tip to measure the statistical nuclear polarization of 19F in CaF2 by magnetic resonance force microscopy (MRFM). With less than 350 uW of dissipated power, we achieve rf magnetic fields over 4 mT at 115 MHz for a sample positioned within 100 nm of the "microwire" rf source. A 200-nm diameter FeCo tip integrated onto the wire produces field gradients greater than 10^5 T/m at the same position. The large rf fields from the broadband microwire enable long rotating-frame spin lifetimes of up to 15 s at 4 K.