The Mermin-Wagner Theorem - Condensed Matter Theory Group

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How symmetry breaking occurs in principle Actors Proof of the Mermin-Wagner Theorem Discussion Now we calculate the double commutator [C, H] , C † − First we will evaluate S + m, H − = − i The Bogoliubov inequality The Mermin-Wagner Theorem + Jim 2S i S z m − S z i S + m − S + mS z + i + bS me −iKRm Using this, we evaluate the double commutator S + m, H − , S − p = + 22 Jipδmp S i S − p + 2S z i S z p − − 2 2 Jmp i + S mS − p + 2S z mS z 2 p + 2 bδmpS z p e −iKRp Andreas Werner The Mermin-Wagner Theorem
How symmetry breaking occurs in principle Actors Proof of the Mermin-Wagner Theorem Discussion The Bogoliubov inequality The Mermin-Wagner Theorem This leads to the following intermediate result for the expectation value we are looking for [C, H] , C † − = e m,p ik(Rm−Rp) S + m, H − , S − p − = 2 2 b z −iKRp Sp e + 2 p 2 Jmp m,p 1 − e −ik(Rm−Rp) + S mS − p + 2S z mS z p Andreas Werner The Mermin-Wagner Theorem
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The Mermin-Wagner Theorem - Condensed Matter Theory Group

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