Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single-atom electron paramagnetic resonance in a scanning tunneling
  microscope driven by a radiofrequency antenna at 4 K   Combining electron paramagnetic resonance (EPR) with scanning tunneling
microscopy (STM) enables detailed insight into the interactions and magnetic
properties of single atoms on surfaces. A requirement for EPR-STM is the
efficient coupling of microwave excitations to the tunnel junction. Here, we
achieve a coupling efficiency of the order of unity by using a radiofrequency
antenna placed parallel to the STM tip, which we interpret using a simple
capacitive-coupling model. We further demonstrate the possibility to perform
EPR-STM routinely above 4 K using amplitude as well as frequency modulation of
the radiofrequency excitation. We directly compare different acquisition modes
on hydrogenated Ti atoms and highlight the advantages of frequency and magnetic
field sweeps as well as amplitude and frequency modulation in order to maximize
the EPR signal. The possibility to tune the microwave-excitation scheme and to
perform EPR-STM at relatively high temperature and high power opens this
technique to a broad range of experiments, ranging from pulsed EPR spectroscopy
to coherent spin manipulation of single atom ensembles.

8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ