Field dependence of the ferromagnetic/superconducting proximity effect in a YBCO/STO/LCMO multilayer (original) (raw)
Related papers
ferromagnet-superconductor heterostructures 1-5 is a topic of intense research. While it is well known that proximity of a ferromagnet suppresses superconducting order in the superconductor, there exist few studies indicating the proximity of a superconductor suppressing ferromagnetic order in a ferromagnet. 6-11 Here we demonstrate a rare observation of the suppression of ferromagnetic order in a La 2/3 Ca 1/3 MnO 3 layer separated from a YBa 2 Cu 3 O 7-δ layer by a thin insulator (SrTiO 3 ). Polarized neutron reflectivity measurements on La 2/3 Ca 1/3 MnO 3 /SrTiO 3 /YBa 2 Cu 3 O 7-δ trilayer deposited on [001] SrTiO 3 single crystal substrates shows the emergence of a thin magnetic "dead" layer in La 2/3 Ca 1/3 MnO 3 adjacent to the insulating layer below its superconducting transition temperature of YBa 2 Cu 3 O 7-δ . Further, the magnetic dead layer grows in thickness when the 2 insulating layer is made thinner. This indicates a possible tunneling of the superconducting order-parameter through the insulating SrTiO 3 inducing modulation of magnetization in La 2/3 Ca 1/3 MnO 3 . Superconductors (SC) and ferromagnetic (FM) heterostructure like SC/FM/SC, are known to exhibit coupling between the SC through a thin intervening FM layer producing what is known as π-state, essentially due to the presence of SC order-parameter in the FM layer, albeit over an extremely short range. 12 However, in thin film hetrostructures of SC cuprates and FM manganites, there are sufficient evidences which suggest that the SC order persists over much longer length scales extending up to 100 Å, 12,13 which is very intriguing by itself. YBa 2 Cu 3 O 7-δ (YBCO) and La 2/3 Ca 1/3 MnO 3 (LCMO) are ideal candidates for growth of epitaxial thin films on a variety of oxide substrates like SrTiO 3 (STO), LaAlO 3 and others. Heterostructures of these materials grown with high interface quality 14, 15 are ideal candidates for investigating the interaction between mutually antagonistic SC and FM orderings. The properties of LCMO/YBCO heterostructures are strongly influenced by a coupling phenomena at the interface, 1-3 which can lead to complex behaviors in these heterostructures such as giant magnetoresistance 4 , transient photo-induced superconductivity 5 and magnetic proximity effects. 6-11 While the competition between the two ordered ground states 1-3,16 leads to suppression of both superconducting and magnetic transition temperatures, 17, 18 a variety of exotic phenomenon have been seen in these heterostrures. 19
New Journal of Physics, 2011
Epitaxial bilayers of ferromagnetic La 2/3 Ca 1/3 MnO 3 (LCMO) and superconducting YBa 2 Cu 3 O 7-δ (YBCO) have been grown on single-crystalline SrTiO 3 (STO) substrates by pulsed laser deposition. The Manganese magnetization profile across the FM layer has been determined with high spatial resolution at low temperatures by X-ray resonant magnetic reflectivity (XRMR). It is found that not only the adjacent superconductor but also the substrate underneath influences the magnetization of the LCMO film at the interfaces at low temperatures. Both effects can be investigated individually by XRMR.
Superconductivity and Ferromagnetism in La0.67Sr0.33MnO3/YBa2Cu3O7Nanosized Heterostructures
Acta Physica Polonica A, 2016
In this work we present recent experimental studies of heterostructures composed of ferromagnetic La0.67Sr0.33MnO3 (LSMO) and superconducting YBa2Cu3O7 (YBCO) multilayers grown by dc sputtering method. The transport and magnetic properties of the large set of heterostructures were investigated in a wide temperature range from 2 to 400 K and in fields up to 12.5 T. The resistivity and the upper critical field were measured for samples with the plane active dimensions 1.5×5 mm 2. The Nernst effect was studied in the mixed state revealing the characteristic temperature dependence of the Nernst signal which was correlated with variation of the upper critical field. We have observed an influence of the magnetic LSMO layer on the superconducting properties of the adjacent YBCO layer which consists in a substantial reduction of the superconducting critical temperature and a small lowering of the upper critical field.
Pramana, 2007
An experimental study of proximity effect in La0.67Sr0.33MnO3-YBa2Cu3O7-La0.67Sr0.33MnO3 trilayers is reported. Transport measurements on these samples show clear oscillations in critical current (Ic) as the thickness of La0.67Sr0.33MnO3 layers (dF) is scanned from ∼ 50Å to ∼ 1100 A. In the light of existing theories of ferromagnet-superconductor (FM-SC) heterostructures, this observation suggests a long range proximity effect in the manganite, modulated by it's weak exchange energy (∼ 2 meV). The observed modulation of the magnetic coupling between the ferromagnetic LSMO layers as a function of dF , also suggests an oscillatory behavior of the SC order parameter near the FM-SC interface.
Ferromagnetic/superconducting proximity effect in La0.7Ca0.3MnO3/YBa2Cu3O7-δ superlattices
Physical Review B, 2003
We study the interplay between magnetism and superconductivity in high quality YBa 2 Cu 3 O 7 (YBCO) / La 0.7 Ca 0.3 MnO 3 (LCMO) superlattices. We find evidence for the YBCO superconductivity depression in presence of the LCMO layers. We show that due to its short coherence length superconductivity survives in the YBCO down to much smaller thickness in presence of the magnetic layer than in low Tc superconductors. We also find that for a fixed thickness of the superconducting layer, superconductivity is depressed over a thickness interval of the magnetic layer in the 100 nm range. This is a much longer length scale than that predicted by the theory of ferromagnetic/superconducting proximity effect.
SciPost Physics Proceedings
We study the magnetic properties and emergence of superconductivity in YBa_22Cu_33O_77 (YBCO)/ La_{0.67}0.67Sr_{0.33}0.33MnO_33 (LSMO) heterostructures. Bilayer films of superconducting layer, YBCO, and ferromagnetic layer, LSMO were grown on SrTiO_{3}3 (STO) (001) substrate using ultrahigh vacuum Pulsed Laser Deposition system. Magnetization data at 100 K as a function of applied magnetic field shows ferromagnetic behaviour due to the LSMO layer. Cooling below 100 K leads to superconductivity in this material; the onset of superconductivity occurs at a temperature, T_{c,SC},Tc,SC, of 86 K for H_{ext}\perp cHext⊥c (in-plane) & 84 K for H_{ext}||cHext||c (out-of-plane) under 100 Oe applied field. In-plane magnetic measurements show significant suppression of diamagnetic behaviour as compared to the out-of-plane measurements. The susceptibility signals are higher for out-of-plane direction. Such strong anisotropy in magnetism and the transition temperatures reveal complex interplay of...
Magnetism and superconductivity in oxide ferromagnet/superconductor heterostructures
physica status solidi (c), 2005
PACS 74.78.Fk, 75.47.Lx, 75.70.Cn Manganite/oxide cuprate supercondutor heterstructures are attractive model system to study coupling and interface effects. After brief summarizing synthesis and characterization this paper presents recent experimental results obtained in investigated manganite/YBa 2 Cu 3 O 7 heterostructures.
Magnetism at the interface between ferromagnetic and superconducting oxides
Nature Physics, 2006
C arefully controlled interfaces between two materials can give rise to novel physical phenomena and functionalities not exhibited by either of the constituent materials alone. Modern synthesis methods have yielded high-quality heterostructures of oxide materials with competing order parameters. Although magnetic correlations at the interface are expected to be important in determining the macroscopic properties of such systems, a quantitative determination of the interfacial magnetization profile has thus far not been reported. Here we examine superlattices composed of the halfmetallic ferromagnet La 2/3 Ca 1/3 MnO 3 and the high-temperature superconductor YBa 2 Cu 3 O 7 by absorption spectroscopy with circularly polarized X-rays and by off-specular neutron reflectometry. The resulting data yield microscopic insight into the interplay of spin and orbital degrees of freedom at the interface. The experiments also reveal an extensive rearrangement of the magnetic domain structure at the superconducting transition temperature. This methodology establishes an incisive probe of the interplay between competing electronic order parameters in oxide heterostructures.
2002
We report on the depression of the superconducting critical temperature of ultra thin YBa2Cu3O7 (YBCO) layers, when their thickness is reduced in presence of La0.7Ca0.3MnO3 (LCMO) magnetic layers in [LCMO (15 u.c.)/ YBCO(N u.c.)] superlattices. The thickness of the manganite layer is kept at 15 unit cells and the YBCO thickness is varied between N=12 and N=1 unit cells. The structural analysis using x-ray diffraction and electron microscopy shows sharp interfaces with little structural disorder. While a critical temperature, Tc=85 K is found for 12 YBCO unit cells, superconductivity is completely suppressed for YBCO layer thickness below 3 unit cells. The possible interaction between superconductivity and magnetism is investigated.
Physical Review B, 2010
We examine the interplay between ferromagnetism and superconductivity in bilayer and trilayer heterostructures based on Co, YBa 2 Cu 3 O 7−␦ ͑YBCO͒, and La 0.7 Ca 0.3 MnO 3 ͑LCMO͒ thin films grown on SrTiO 3 substrates with typical thicknesses of 10-15 nm. We have measured magnetoresistance below the resistivesuperconducting onset of the YBCO. Naturally oxidized antiferromagnetic CoO top layer films give rise to pronounced exchange bias, modifying the coercive field of the Co by several hundred Oe. This allows separating effects at coercivity, such as stray fields, from those of parallel vs. antiparallel magnetic alignment between top and bottom ferromagnetic layers. In bilayers of Co/YBCO and of LCMO/YBCO, we observe a small magnetoresistance peak centered at the coercive field of the ferromagnetic layer of at most 20%, which we attribute to the effect of stray fields generated in the domain state of the ferromagnet. In the case of the CoO/ Co/ YBCO/ LCMO/ SrTiO 3 trilayer, aside from the peaks at coercivity, we observe a well-defined plateau of the magnetoresistance extending between the coercive fields of the LCMO and Co, with a width that is modified by the exchange-biased Co layer. Reactivity between Co and YBCO at the interface gives rise to a progressive deterioration in the superconducting transition temperature. Aged samples display magnetoresistance peaks at the coercive fields of the Co and LCMO characteristic of stray fields without the magnetoresistance plateau between them.