Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Paramagnetic to ferromagnetic phase transition in lightly Fe-doped
  Cr$_2$B   Cr$_2$B displays temperature independent paramagnetism. We induce
ferromagnetism by replacing less than $3\,\%$ of the Cr atoms by Fe. By the
lowest Fe doping level made, Curie-Weiss behavior is observed; $\Theta_{CW}$
changes from $-20\,$K for $0.5\,\%$ Fe-doped Cr$_2$B to positive values of
about 50 K by $5\,\%$ Fe doping. The ferromagnetic T$_C$ is 8 K for $2.5\,\%$
Fe doping and increases linearly to 46 K by $5\,\%$ doping; we infer that a
quantum phase transition occurs near the $2.0\,\%$ Fe level. Magnetic
fluctuations at the intermediate doping levels are reflected in the linear
resistance and an anomalous heat capacity at low temperatures. Imaging and
chemical analysis down to the atomic scale show that the Fe dopant is randomly
distributed.

33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph