Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface excitations relaxation in the Kondo insulator
  Sm$_{1-x}$Gd$_{x}$B$_{6}$   The interplay between non-trivial topological states of matter and strong
electronic correlations is one of the most compelling open questions in
condensed matter physics. Due to experimental challenges, there is an
increasing desire to find more microscopic techniques to complement the results
of more traditional experiments. In this work, we locally explore the Kondo
insulator Sm$_{1-x}$Gd$_{x}$B$_{6}$ by means of electron spin resonance (ESR)
of Gd$^{3+}$ ions at low temperatures. Our analysis reveals that the Gd$^{3+}$
ESR line shape shows an anomalous evolution as a function of temperature,
wherein for highly dilute samples (x $\approx$ 0.0002) the Gd$^{3+}$ ESR line
shape changes from a localized ESR local moment character to a diffusive-like
character. Upon manipulating the sample surface with a focused ion beam we
demonstrate, in combination with electrical resistivity measurements, that the
localized character of the Gd$^{3+}$ ESR line shape is recovered by increasing
the penetration of the microwave in the sample. This provides compelling
evidence for the contribution of surface or near-surface excitations to the
relaxation mechanism in the Gd$^{3+}$ spin dynamics. Our work brings new
insights into the importance of non-trivial surface excitations in ESR, opening
new routes to be explored both theoretically and experimentally.

1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom