Exploring possible ferromagnetism of the LaAlO3/SrTiO3 interface

Abstract

We report on extensive investigations of magnetism at the n-type LaAlO 3 /SrTiO 3 interface performed by utilizing a spectrum of local and integrative analytical techniques: Scanning superconducting quantum interference device microscopy, polar Kerr magnetometry, ferromagnetic resonance, and magnetic torque magnetometry. The samples originated from the same wafers. For nominally fully oxidized samples, we find that the mere presence of the conducting interface does not induce magnetism to values exceeding already present magnetic signals originating from the substrates, irrespective of the measurement technique. With the controlled introduction of oxygen vacancies, however, the different analytical techniques with their inherently different sensitivities and potential interactions with possible magnetic moments in the samples yield different results concerning the existence of magnetism. These unexpected differences obtained with the various measurement techniques are a possible source of the disagreement in the literature about the existence of ferromagnetism at LaAlO 3 /SrTiO 3 interfaces.

High-temperature superconductivity and its robustness against magnetic polarization in monolayer FeSe on EuTiO3

“…The buried interface and low T c (<0.3 K) have limited the study and potential control of the coupling between spin and charge. A recent study casts some doubt on the origin of the ferromagnetism of LaAlO 3 /SrTiO 3 , suggesting that magnetism is induced by extrinsic defects and not an intrinsic property of the interface 10 .…”

Studying Quantum Materials with Scanning SQUID Microscopy

“…When analyzing magnetic systems, the magnetic moment distribution, M(r), rather than the magnetic field, B(r), is often the quantity of interest. When magnetic moments are sparse, a point dipole model can be fitted to each localized signal, and the moment distribution can be extracted from the SSM images (Figure 3b; 41,78,79,93). However, for a general M(r), the reconstruction process from the B(r) data is nonunique (94).…”

Microscopic origin of the Dynes parameterΓof theLaAlO3–SrTiO3interface superconductor

“…Magnetic effects can be present at the LaAlO 3 -SrTiO 3 interface (see Ref. [50] and references therein), but the spin-scattering rate is low. The experimentally measured spin lifetime is ∼150 ps and it has a weak temperature dependence for 2 < T < 15 K [41,51].…”