Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coupling of Surface Acoustic Waves to a Two Dimensional Electron Gas   When a surface acoustic wave (SAW) is coupled piezoelectrically to a two
dimensional electron gas (2DEG), a velocity shift and attenuation of the SAW
are induced that reflect the conductivity of the 2DEG. This paper considers the
case of a AlGaAs heterostructure with a 2DEG a distance $d$ from a (100)
surface of the crystal where the SAWs are propagated in the [011] direction at
wavevector $q$. It is found that the velocity shift $\Delta v_s$ and the
attenuation coefficient $\kappa$ satisfy the well known equation $(\Delta
v_s/v_s) - (i \kappa/q) = (\alpha^2/2)/\left(1 + \frac{i \sigma_{xx}(q,\omega)}
{\sigma_m}\right)$ where $\sigma_{xx}(q,\omega)$ is the complex conductivity at
wavevector $q$ and frequency $\omega = v_s q$ with $v_s$ the velocity of the
SAW. The coefficients $\alpha$ and $\sigma_m$ are calculated and it is found
that $\alpha$ has a nontrivial dependence on the product $qd$.

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The categories of this paper are: acc-phys
16
The categories of this paper are: stat
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio