2,281 reputation
423
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location Santa Barbara, CA
age 28
visits member for 2 years, 7 months
seen 16 hours ago

I am a postdoc at Kavli Institute for Theoretical Physics, University of California, Santa Barbara. My major is in condensed matter physics.


59m
awarded  Explainer
1d
answered Why is $\hat{p} \circ \hat{p}$ the operator corresponding to $p^2$?
Sep
27
revised Why are most ferromagnets metals while antiferromagnets are insulators?
deleted 1 character in body
Sep
27
revised Why are most ferromagnets metals while antiferromagnets are insulators?
add a figure of superexchange
Sep
27
comment Why are most ferromagnets metals while antiferromagnets are insulators?
@Jonas Your model assumes perfect nesting and fully gapped SDW, which generally not true. In nature, there are many SDW metals, like the parent compounds of iron-based superconductors (e.g. $\text{BaFe}_2\text{As}_2$). So it is not always true that "AFM gives rise to a band gap while FM does not".
Sep
27
answered Why are most ferromagnets metals while antiferromagnets are insulators?
Sep
26
comment Projection Method in Hubbard model
@SlipStream Second order means the electron is only allowed to hop twice. For the first t, the electron hops to one nearest site, and for the second t, the electron has no choice but to hop back to its original site, otherwise the electron will not end up with the single occupied configuration, and hence not contributing to the low-energy theory. So this only involves two sites.
Sep
25
reviewed Approve suggested edit on Torque on the earth
Sep
25
comment Projection Method in Hubbard model
@SlipStream Yes, but to the second order perturbation in (t/U), one only need to consider two sites. All the electrons on the other sites are just by-standing and do nothing.
Sep
24
awarded  Autobiographer
Sep
24
answered Projection Method in Hubbard model
Sep
22
awarded  Popular Question
Sep
21
reviewed Approve suggested edit on If a truck collides with a car, can the truck experience a larger force?
Sep
21
comment Is there a critical order of the Abelian gauge theory in (2+1)D
@K-boy I am assuming your first limit.
Sep
20
reviewed Approve suggested edit on Does gravity slow the expansion of the universe?
Sep
19
reviewed Approve suggested edit on Why is the sky not purple?
Sep
17
comment compressibility of cold atoms in optical lattices
@rain Because the compressibility is actually defined as $\kappa=k_B T\partial_\mu\langle n\rangle$, the factor $k_B T$ is required to make $\kappa$ a dimensionless constant. So $\kappa=\langle n^2\rangle-\langle n\rangle^2$ is well-defined at zero temperature.
Sep
16
comment Do waves accelerate?
@CuriousOne Obviously you did not read the post carefully. We are talking about a generic excited state of the electron, but not its ground state. I do not see any inappropriateness in my answer. However if you feel that something is wrong, please discuss here and make edit to help improve the answer, but not rudely vote down.
Sep
16
awarded  Organizer
Sep
16
revised compressibility of cold atoms in optical lattices
added 52 characters in body; edited tags