Adapting Planck's route to investigate the thermodynamics of the spin-half pyrochlore Heisenberg antiferromagnet

Multiloop functional renormalization group approach to quantum spin systems

“…The S = 1/2 nearest neighbor Heisenberg antiferromagnet presents itself as a critically outstanding problem in frustrated magnetism. There is mounting evidence that it hosts a quantum spin liquid ground state [48,[88][89][90][91][92], however, deciphering its nature has proven to be notoriously difficult [93][94][95][96][97]. In a recent = 1 pf-FRG calculation [48], it was shown that the RG flow of the susceptibility does not develop a divergence at finite Λ for any wave vector in the extended Brillouin zone, indicating quantum paramagnetic behavior.…”

Logarithmic divergent specific heat from high-temperature series expansions: Application to the two-dimensional XXZ Heisenberg model

“…Finally, high-temperature series expansion (HTSE) methods operate directly in the thermodynamic limit but cannot reach very low temperatures, a limitation that becomes more restrictive when there are singularities in the thermodynamic functions due to the presence of a finite-temperature phase transition. When there is no finite-temperature phase transition, methods have been proposed to extrapolate the HTSE of thermodynamic functions down to T = 0 [26][27][28][29], relying on some knowledge about the ground state (such as the type of order and ground-state energy). These methods have proven to be useful for understanding experiments [30][31][32][33][34][35].…”

Signatures of finite-temperature mirror symmetry breaking in the S=12 Shastry-Sutherland model

“…For example, the number of spins we can treat is limited to about 24 in the case of an S = 1/2 quantum spin system. For overcoming such the situation, alternative numerical methods without ensemble average [1][2][3][4][5][6] have also been developed and used historically to investigate the thermal nature of the quantum frustrated spin systems, such as triangular [6][7][8][9], kagome [5][6][7][8][10][11][12][13][14][15][16][17], and pyrochlore [18][19][20] magnets. In particular, the method using a typical pure state has got attention recently because it has been proven in different and independent literatures that a single pure state can represent the thermal equilibrium in the thermodynamic limit [2,[4][5][6].…”

“…Excellent magnetic susceptibility [8,12] and specific-heat [13] measurements made at this time were used to estimate the coupling ratio as J/J D ' 0.635, thereby placing SrCu 2 (BO 3 ) 2 rather close to the dimer-plaquette QPT. Detailed experiments performed in the intervening two decades have revealed a spectacular series of magnetization plateaus [8,[14][15][16][17][18][19][20][21], as well as a curious redistribution of spectral weight at temperatures very low on the scale of the triplon gap [11,22]. Of most interest to our current study is the result [23] that an applied pressure makes it possible to increase the ratio J/J D to the extent that, at approximately 1.9 GPa, the material is pushed through the QPT into a plaquette phase.…”