Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comment on "Quantized Orbital Angular Momentum Transfer and Magnetic
  Dichroism in the Interaction of Electron Vortices with Matter"   It was claimed (Lloyd et al., PRL 108 (2012) 074802) that energy loss
magnetic chiral dichroism (EMCD) with electron vortex beams is feasible, and
has even advantages over the standard setup with Bragg diffracted waves. In
this Comment, we show that Lloyd et al. ignored an important constraint on the
proposed selection rule for the transfer of angular momentum in the
interaction, namely that it is only valid for an atom located in the very
center of the vortex. As an experimental consequence, the EMCD signal will only
be strong for extremely small nanoparticles of 1 to 2 nm diameter.

31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph