Robust stripes in mixed-dimensional variants of the t-J model*

The interplay of spin and motional degrees of freedom is at the heart of many strongly correlated quantum materials. In the underdoped Hubbard model, there exists strong evidence for the formation of inhomogeneous order in the ground sate, such as stripes, close to optimal doping and in subtle competition with superconductivity. However, critical temperatures for stripe formation are too low to be reached with current state-of-the-art experiments. Motivated from the versatility of ultracold atoms in optical lattices, we shall look at stripe order of the t-J model of mixed dimensionality (mixD), where charge carriers are restricted to move only in one direction, whereas magnetic interactions are two-dimensional. Using finite temperature density matrix renormalization group methods via symmetry conserving purification schemes, we analyze the order of the mixD setting for various hole densities and map out the phase diagram. Below critical temperatures in the range of the magnetic coupling J, we predict a stable stripe phase, featuring incommensurate magnetic order and oscillating hole density profiles in the hopping direction over the whole range of the simulated system size. We further characterize the striped ground state under inhomogeneous hole doping in the ladder legs, leading to the formation of chargon-chargon and chargon-spinon bound states in the mixD t-Jz and t-J model, respectively.