Fermi surface reconstruction by dynamic magnetic fluctuations and spin-charge separation near anO(3)quantum critical point

Abstract

Stimulated by the small/large Fermi surface controversy in the cuprates, we consider a small number of holes injected into the bilayer antiferromagnet. The system has an O(3) quantum critical point (QCP) separating the magnetically ordered and the magnetically disordered phases. We demonstrate that nearly critical quantum magnetic fluctuations can change the Fermi surface topology and also lead to spin charge separation (SCS) in two dimensions. We demonstrate that in the physically interesting regime there is a magnetically driven Lifshitz point (LP) inside the magnetically disordered phase. At the LP the topology of the hole Fermi surface is changed. The position of the LP, while being close to the position of the QCP, generally differs. Dependent on the additional hole hopping integrals t and t , the LP can be located in the magnetically ordered phase and/or in the magnetically disordered phase. We also demonstrate that in this regime the hole spin and charge necessarily separate when approaching the QCP. The considered model sheds light on generic problems concerning the physics of the cuprates.

Carrier dynamics in doped bilayer iridates near magnetic quantum criticality

“…In such scenarios, the so-called self-consistent Born approximation (SCBA) has established itself as a method of choice. 16,17,[37][38][39] The key idea is to resum a certain subset of diagrams, namely those consisting of non-crossing triplon loops (hence also called non-crossing approximation, NCA). This has to be done implicitly, and leads to the self-energy 40…”

“…This motivates us to study the dynamics of doped charge carriers in spin-orbit-coupled bilayer magnets in some detail-this is the purpose of our paper. To this end, we consider a suitable t-J model and generalize earlier work on single-carrier dynamics [15][16][17] to include effects of SOC. Since small doping pushes (Sr 1−x La x ) 3 Ir 2 O 7 into the paramagnetic phase, 7,13 we focus on the paramagnetic nearly critical regime of the undoped host magnet.…”

Impurity-induced magnetization in a three-dimensional antiferromagnet at the quantum critical point

“…(15) Vanishing quasiparticle residue is the first signal of delocalization of the impurity-induced spin cloud and therefore indication of SCS. 22 Typical value of the impurity-magnon coupling constant λ can be estimated on the basis of the lattice model, shown in Fig. 1.…”

“…However, SCS exists in 2D models, such as hole-doped AF [18][19][20][21] . Furthermore, the recent research 22 reports pronounced SCS in the vicinity of the magnetic QCP. In the latter case, the precise meaning of SCS is different from SCS in Tomonaga-Luttinger liquid.…”

Bond particle theory for the pseudogap phase of underdoped cuprates

“…Constructing a theory which gives a fermi surface with a volume proportional to x without invoking backfolding of a free-electron fermi surface is not achieved easily. Various authors have proposed that a fluctuating rather than a static order order parameter is already sufficient to backfold the fermi surface [49][50][51][52][53] or that short-range antiferromagnetic correlations may cause the pseudogap 54,55 . Hole pockets can also be produced by a phenomenological ansatz for the self-energy 56 and it has also been proposed that the origin of the pseudogap is checkerboard-type CDW order 57 .…”