Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The quantum ferromagnetic transition in a clean Kondo lattice is
  discontinuous   The Kondo-lattice model, which couples a lattice of localized magnetic
moments to conduction electrons, is often used to describe heavy-fermion
systems. Because of the interplay between Kondo physics and magnetic order it
displays very complex behavior and is notoriously hard to solve. The
ferromagnetic Kondo-lattice model, with a ferromagnetic coupling between the
local moments, describes a phase transition from a paramagnetic phase to a
ferromagnetic one as a function of either temperature or the ferromagnetic
local-moment coupling. At zero temperature, this is a quantum phase transition
that has received considerable attention. It has been theoretically described
to be continuous, or second order. Here we show that this belief is mistaken;
in the absence of quenched disorder the quantum phase transition is first
order, in agreement with experiments, as is the corresponding transition in
other metallic ferromagnets.

11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
23
The categories of this paper are: solv-int