Electric field control of exchange bias in multiferroic epitaxial heterostructures

The magnetic exchange bias between epitaxial thin films of the multiferroic (antiferromagnetic and ferroelectric) hexagonal YMnO3 oxide and a soft ferromagnetic (FM) layer is used to couple the magnetic response of the ferromagnetic layer to the magnetic state of the antiferromagnetic one. We will show that biasing the ferroelectric YMnO3 layer by an appropriate electric field allows modifying and controlling the magnetic exchange bias and subsequently the magnetotransport properties of the FM layer. This finding may contribute to pave the way towards a new generation of electric-field controlled spintronics devices.Comment: 15 pages, 5 figures, submitte

Electric field effects on magnetotransport properties of multiferroic Py/YMnO3/Pt heterostructures

We report on the exchange bias between antiferromagnetic and ferroelectric hexagonal YMnO3 epitaxial thin films sandwiched between a metallic electrode (Pt) and a soft ferromagnetic layer (Py). Anisotropic magnetoresistance measurements are performed to monitor the presence of an exchange bias field. When the heteroestructure is biased by an electric field, it turns out that the exchange bias field is suppressed. We discuss the dependence of the observed effect on the amplitude and polarity of the electric field. Particular attention is devoted to the role of current leakage across the ferroelectric layer.Comment: Accepted for publication in Philosophical Magazine Letters (Special issue on multiferroics

Dielectric characterization of multiferroic magnetoelectric double-perovskite Y(Ni0.5Mn0.5)O3 thin films

We report on the functional properties of the Y(Ni0.5Mn0.5)O3 epitaxial thin films, growth by pulsed laser deposition, observing the clear features of their ferroelectric and ferromagnetic nature at cryogenic temperature. The characterization of temperature-dependent complex impedance spectroscopy has shown a dielectric anomaly around the ferromagnetic Curie temperature (100 K) indicative of coupling between magnetic and electric orders.The financial support by the Ministerio de Ciencia e Innovacion of the Spanish Government (Grant No. BES-2009-028641 and Project Nos. MAT2011-29269-C03-03, NANOSELECT, MAT2014-56063-C2-2-R, CSD2007-00041, MAT2015-73839-JIN, and IMAGINE CSD2009-00013) and Generalitat de Catalunya (2014 SGR 734) is acknowledged. E.C. would like to thank the National Science Centre of Poland under the PRELUDIUM (UMO-2015/17/N/ST5/ 01988) for financial support. I.F. acknowledges the financial support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496), and also the Juan de la Cierva–Incorporacion postdoctoral fellowship (IJCI- 2014-19102) from the Spanish Ministry of Economy and Competitiveness of Spanish Government.Peer reviewe

Strain-driven non-collinear magnetic ordering in orthorhombic epitaxial YMnO3 thin films

We show that using epitaxial strain and chemical pressure in orthorhombic YMnO3 and Co-substituted (YMn0.95Co0.05O3) thin films, a ferromagnetic response can be gradually introduced and tuned. These results, together with the measured anisotropy of the magnetic response, indicate that the unexpected observation of ferromagnetism in orthorhombic o-RMnO3 (R= Y, Ho, Tb, etc) films originates from strain-driven breaking of the fully compensated magnetic ordering by pushing magnetic moments away from the antiferromagnetic [010] axis. We show that the resulting canting angle and the subsequent ferromagnetic response, gradually increase (up to ~ 1.2\degree) by compression of the unit cell. We will discuss the relevance of these findings, in connection to the magnetoelectric response of orthorhombic manganites.Comment: Text + Figs Accepted in J. Appl. Phy

Resistance to three thrips species in <i>Capsicum</i> spp. depends on site conditions and geographic regions

Capsicum species are commercially grown for pepper production. This crop suffers severely from thrips damage and the identification of natural sources of thrips resistance is essential for the development of resistant cultivars. It is unclear whether resistance to Frankliniella occidentalis as assessed in a specific environment holds under different conditions. Additionally, other thrips species may respond differently to the plant genotypes. Screening for robust and general resistance to thrips encompasses testing different Capsicum accessions under various conditions and with different thrips species. We screened 11 Capsicum accessions (C. annuum and C. chinense) for resistance to F. occidentalis at three different locations in the Netherlands. Next, the same 11 accessions were screened for resistance to Thrips palmi and Scirtothrips dorsalis at two locations in Asia. This resulted in a unique analysis of thrips resistance in Capsicum at five different locations around the world. Finally, all accessions were also screened for resistance to F. occidentalis in the Netherlands using a leaf disc choice assay, allowing direct comparison of whole plant and leaf disc assays. Resistance to F. occidentalis was only partially consistent among the three sites in the Netherlands. The most susceptible accessions were consistently susceptible, but which accession was the most resistant differed among sites. In Asia, one C. chinense accession was particularly resistant to S. dorsalis and T. palmi, but this was not the most resistant accession to F. occidentalis. Overall, resistance to F. occidentalis correlated with S. dorsalis but not with T. palmi resistance in the C. annuum accessions. Damage inflicted on leaf discs reflected damage on the whole plant level. Our study showed that identifying broad spectrum resistance to thrips in Capsicum may prove to be challenging. Breeding programmes should focus on developing cultivars suitable for growing in defined geographic regions with specific thrips species and abiotic conditions

Exchange biasing and electric polarization with YMnO3

We report on the growth and functional characterization of epitaxial thin films of the multiferroic YMnO3. We show that using Pt as a seed layer on SrTiO3(111) substrates, epitaxial YMnO3 films (0001) textured are obtained. An atomic force microscope has been used to polarize electric domains revealing the ferroelectric nature of the film. When a Permalloy layer is grown on top of the YMnO3(0001) film, clear indications of exchange bias and enhanced coercivity are observed at low temperature. The observation of coexisting antiferromagnetism and electrical polarization suggests that the biferroic character of YMnO3 can be exploited in novel devices.Comment: 15 pages, 4 figures, Applied Physics Letters (in press

Seaweed aquaculture through the lens of gender: Participation, roles, pay and empowerment in Bantayan, Philippines

Aquaculture is one of the fastest growing food-producing sectors worldwide. Of particular importance is the cultivation of seaweed, particularly in East and Southeast Asia where seaweeds dominate the production market, and are key for coastal communities both as main livelihood source and as alternative or supplementary income to fisheries. Women play a crucial role in various segments of the seaweed aquaculture value chain; yet few researchers have empirically examined the gendered impacts of women’s participation in aquaculture. Using the case study of Bantayan Island, in the Philippines, the objective of this study is to deepen our understanding of the impact of women’s participation in aquaculture by specifically investigating their roles, remuneration and empowerment related to the production node of seaweed aquaculture. Adopting a novel research approach, which combines the outcomes of a focus group discussion and the data collected through two questionnaires, we provide a comprehensive and robust understanding of gender issues in aquaculture. Results of the economic analysis of labour costs indicate that women constitute most of the workforce but are paid less than men; the average gender pay gap is 55.4%. Moreover, our study finds that there is a well-established gendered division of labour in seaweed aquaculture. Greater female participation is not mirrored by more women in leadership roles and decision-making power in the workplace, although participation may have a positive impact on female intrahousehold empowerment. An important contribution of our analysis is to show that gender stereotypes in aquaculture production persist and they affect roles, wages and decision-making power. Acknowledging the fundamental contribution of women in aquaculture can inform the development of gender-sensitive indicators, supporting the measurement of progress towards relevant Targets of the fifth Sustainable Development Goal (“ Achieve gender equality and empower all women and girls ”), therefore mainstreaming gender into resource management, and poverty alleviatio