- #1
georgeD123
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A free electron gas would have zero magnetoresistance; it takes two carrier types to get ordinary magnetoresistance, which is always positive in sign.
Beal-Monod and Weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spin-flip scattering of conduction electrons off the impurities.
Their argument seems to be the following:
Consider an electron scattering off of a magnetic impurity, in the presence of an applied field, in the case where μH<kT.
An electron in initial state ki,↓ scatters into state kf,↑ off of an impurity, whose spin is reduced to compensate. Conservation of energy gives ki=kf.The net change in electron energy should be -2μH.
Since only electrons within kT of the Fermi Level can participate in scattering processes, they claim that this process should be forbidden. I don't see why.
The original energy was at least εF±kT. The final energy should then be εF±kT-2μH. If μH<kT, then this should be guaranteed to remain within kT of the Fermi Level.
What am I thinking about wrong? Thank you!
(For what it's worth their exact words are "the final spin-up electron has a total energy (kinetic+Zeeman) less than εF by at least 2μH-kT." I just can't quite make the signs jibe or I am thinking about something wrong. Thanks!)
Beal-Monod and Weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spin-flip scattering of conduction electrons off the impurities.
Their argument seems to be the following:
Consider an electron scattering off of a magnetic impurity, in the presence of an applied field, in the case where μH<kT.
An electron in initial state ki,↓ scatters into state kf,↑ off of an impurity, whose spin is reduced to compensate. Conservation of energy gives ki=kf.The net change in electron energy should be -2μH.
Since only electrons within kT of the Fermi Level can participate in scattering processes, they claim that this process should be forbidden. I don't see why.
The original energy was at least εF±kT. The final energy should then be εF±kT-2μH. If μH<kT, then this should be guaranteed to remain within kT of the Fermi Level.
What am I thinking about wrong? Thank you!
(For what it's worth their exact words are "the final spin-up electron has a total energy (kinetic+Zeeman) less than εF by at least 2μH-kT." I just can't quite make the signs jibe or I am thinking about something wrong. Thanks!)