Electron-spin resonance probe based on a 100 μm planar microcoil

Abstract

We describe the fabrication and the performance of a microcoil-based probe for electron spin resonance (ESR) spectroscopy on micrometer sized samples. The probe consists of a 100 μm planar microcoil fabricated on a glass substrate, tuned and matched at 1.4 GHz (L band) using miniaturized ceramic capacitors. We performed continuous wave ESR experiments on samples having a volume between (100 μm)3 and (10 μm)3. At 300 K, we achieved a spin sensitivity of about 1010 spins/G Hz1/2, which is comparable to that of commercial ESR spectrometers operating at 9 GHz (X band). The results reported in this article suggest that microcoil-based probes might represent a valid alternative to conventional microwave cavities for ESR studies of sample of the order of (100 μm)3 and smaller.

Planar microresonators for EPR experiments

“…The cw EPR operation of a microcoil-based probe on micrometer-sized samples was recently demonstrated at 1.4 GHz (L band) [29]. At 300 K, a spin sensitivity of about 10 10 spins AE G À1 Hz À1/2 was achieved, which is already comparable to that of a commercial X-band spectrometer.…”

“…For the microstrip resonator with an incorporated microcoil the signal calculated using Eq. (2) of [29] exceeds the experimentally observed signal by a factor of 3, and for the PMR with the radial stub by a factor 1.5. The calculation was done assuming that the DPPH samples are far from saturation, whereas in the experiment they are partially saturated.…”

“…The current layout of the microresonator should be scalable down to tens of micrometers. This would result in a spin sensitivity of about 10 6 spins AE G À1 Hz À1/2 [29]. Recent achievements in the photonic crystals development demonstrated the possibility to operate split rings, nanometer sized planar LC resonators at THz frequencies [40].…”

“…If we define the spin sensitivity as the minimum number of detectable spins for a frequency bandwidth f of 1 Hz [29] …”

Microwave band on-chip coil technique for single electron spin resonance in a quantum dot

“…Concerning the development of on-chip MW structures, there are already many studies performed on the on-chip spiral coil structure [16]. We followed these studies and developed the on-chip spiral coil shown in Fig.…”