Interface Magnetism in Epitaxial BiFeO₃-La_0.7Sr_0.3MnO₃ Heterostructures Integrated on Si(100)

Abstract

We report on the heteroepitaxial growth of ferroelectric (FE)-antiferromagnetic (AFM) BiFeO3 (BFO) on ferromagnetic La0.7Sr0.3MnO3 (LSMO), integrated on Si(100) using pulsed laser deposition via the domain matching epitaxy paradigm. The BFO/LSMO films were epitaxially grown on Si(100) by introducing epitaxial layers of SrTiO3/MgO/TiN. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photo absorption spectroscopy, and atomic force microscopy were employed to fully characterize the samples. Furthermore, we have investigated the magnetic behavior of this five layer heterostructure, in which a d(5) system (Fe(3+)) manifested in FE-AFM BFO is epitaxially conjoined at the interface to a multivalent transition metal ion such as Mn(3+)/Mn(4+) in LSMO. The temperature- and magnetic field-dependent magnetization measurements reveal an unexpected enhancement in magnetic moment and improved magnetic hysteresis squareness originating from the BFO/LSMO interface. We observe a stronger temperature dependence of HEB when the polarity of field cooling is negative as compared to positive field cooling. We believe such an enhancement in magnetic moment and magnetic coupling is likely directly related to an electronic orbital reconstruction at the interface and complex interplay between orbital and spin degrees of freedom, similar to what has previously been reported in the literature. Future work will involve the linearly polarized X-ray absorption measurements to prove this hypothesis. This work represents a starting step toward the realization of magneto-electronic devices integrated with Si(100).

Ferromagnetic oxide heterostructures on silicon

“…The study of interface magnetic coupling in bilayers involving manganites with other layers has been widely reported in the past. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Similar enhancement in switching field (7309 Oe) was observed [19] when the SRO layer is interfaced with the ferroelectric and antiferromagnetic BiFeO 3 layers. It should be noted that these switching field values are much higher than the values observed for individual layers.…”

Multifunctional heterostructures integrated on Si (100)

“…However, using a TiN, MgO and STO buffer layer based on the DME paradigm, 18,19 the authors have demonstrated that multi-layer oxide heterostructures can be successfully deposited on Si(100). [23][24][25] The samples studied here were BFO/LSMO/STO/MgO/TiN/Si(100), LSMO/STO/MgO/TiN/Si(100) and BFO/STO/MgO/TiN/Si(100), which were labelled as samples A, B and C, respectively. Si (004) Intensity: a.u.…”

Influence of Negative Field Cooling on the Exchange Bias Properties of Potassium Split Graphene Nanoribbons

“…Essentially, the hysteresis loop shifts along the negative field axis as shown in inset of Fig. 1 heterostructures [21]. Observed positive exchange bias can be explained on the basis of the competing exchange interaction between the FM -AFM phases and the coupling between an applied magnetic field -and spins which are aligned antiferromagnetically at the surface [4].…”

“…A plethora of experimental investigations have proved that negative magnetic field cooling (NFC) would have pronounced effects on exchange bias properties [21][22][23]. Such marked results pertinent to exchange bias have been attributed to existence of pinned and rotatable spins at the interfaces.…”