Magnetic Field Induced Semimetal-to-Canted-Antiferromagnet ...
Magnetic Field Induced Semimetal-to-Canted-Antiferromagnet ...
Magnetic Field Induced Semimetal-to-Canted-Antiferromagnet ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Contents<br />
1 Introduction 5<br />
2 Mean <strong>Field</strong> Treatment 7<br />
2.1 The model Hamil<strong>to</strong>nian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7<br />
2.2 Examination of the transversal susceptibility . . . . . . . . . . . . . . . . . 9<br />
2.3 Mean field decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13<br />
2.4 Meanfield phase transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16<br />
2.5 Spectral function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18<br />
3 Functional Integral Formulation 25<br />
3.1 The partition function as a path integral over imaginary time . . . . . . . . 25<br />
3.2 Introduction of the auxiliary field . . . . . . . . . . . . . . . . . . . . . . . . 27<br />
3.3 Discrete Hubbard-Stra<strong>to</strong>novich transformation . . . . . . . . . . . . . . . . 28<br />
3.4 Formulation of the partition function . . . . . . . . . . . . . . . . . . . . . . 29<br />
4 The Projec<strong>to</strong>r QMC Method 31<br />
4.1 The trial wave function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31<br />
4.2 Observables in the PQMC algorithm . . . . . . . . . . . . . . . . . . . . . . 33<br />
4.2.1 Equal time Green function G(τ) . . . . . . . . . . . . . . . . . . . . 33<br />
4.2.2 Imaginary time displaced Green function G(τ′, τ) . . . . . . . . . . . 35<br />
4.2.3 Efficient calculation of G(τ′, τ) . . . . . . . . . . . . . . . . . . . . . 36<br />
5 Outline of the Monte Carlo Technique 39<br />
5.1 The Monte Carlo sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . 39<br />
5.1.1 Implementation in the algorithm . . . . . . . . . . . . . . . . . . . . 41<br />
5.2 The PQMC algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42<br />
5.2.1 Efficient realization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44<br />
6 Results 47<br />
6.1 Static observables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47<br />
6.2 Excitation spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48<br />
3