Spin and motion dynamics with zigzag ion crystals in transverse magnetic field gradients

We investigate the dynamics of ion crystals in zigzag configuration in transverse magnetic field gradients. A surface-electrode Paul trap is employed to trap $^{40}$Ca$^+$ ions and features submerged wires to generate magnetic field gradients of up to 16.3(9) T/m at the ions position. With the gradient aligned in the direction perpendicular to the axis of weakest confinement, along which linear ion crystals are formed, we demonstrate magnetic field gradient induced coupling between the spin and ion motion. For crystals of three ions across their linear-to-zigzag structural transition we perform sideband spectroscopy upon directly driving the spins with a radiofrequency field. Furthermore, we observe the rich excitation spectrum of vibrational modes in a planar crystal comprised of four ions.