Strong spin-lattice coupling in multiferroic HoMnO3_{3}: Thermal expansion anomalies and pressure effect

Evidence for a strong spin-lattice coupling in multiferroic HoMnO_3 is derived from thermal expansion measurements along a- and c-axis. The magnetoelastic effect results in sizable anomalies of the thermal expansivities at the antiferromagnetic (T_N) and the spin rotation (T_{SR}) transition temperatures as well as in a negative c-axis expansivity below room temperature. The coupling between magnetic orders and dielectric properties below T_N is explained by the lattice strain induced by the magnetoelastic effect. At T_{SR} various physical quantities show discontinuities that are thermodynamically consistent with a first order phase transition

Feasibility Study of Establishing an Artificial Insemination (Ai) Center for Carabaos in San Ildefonso, Bulacan, Philippines

The productivity of the carabao subsector is influenced by several constraints such as social,technical, economic and policy factors. The need to enhance the local production of carabaos will helplocal farmers to increase their income. Thus, producing thorough breeds of carabaos and improving itgenetically is the best response to these constraints. This study was conducted to present the feasibilitystudy of establishing an Artificial Insemination (AI) Center and its planned area of operation in Brgy.San Juan, Ildefonso, Bulacan. The market, production, organizational and financial viability of operatingthe business would also be evaluated. This particular study will provide insights in establishing an AICenter. Included in this study is the identification of anticipated problems that could affect the businessand recommendation of specific courses of action to counteract these possible problems. Primary datawere obtained through interviews with key informants from the Philippine. Carabao Center (PCC). Togain insights about the present status of an AI Center, interviews with the technicians of PCC and privatefarm were done to get additional information. Secondary data were acquired from various literatures andfrom San Ildefonso Municipal Office. The proposed area would be 1,500 square meters that would beallotted for the laboratory and bullpen. The AI Center will operate six days a week and will be openedfrom 8 AM until 5 PM. However, customers or farmers can call the technicians beyond the office hoursin case of emergency. The total initial investment of Php 3,825,417.39 is needed in establishing the AICenter. The whole amount will be sourced from the owner\u27s equity. Financial projection showed an IRRof 30% with a computed NPV of Php 2,415,597.00 and a payback period of 3.97 years. Based on all themarket, technical, organizational, financial factors, projections and data analysis, it is said that thisbusiness endeavor is viable and feasible

Low temperature dielectric anomalies in HoMnO_3: The complex phase diagram

The dielectric constant of multiferroic hexagonal HoMnO_3 exhibits an unprecedented diversity of anomalies at low temperatures (1.8 K< T <10 K) and under external magnetic fields related to magnetic phase transitions in the coupled system of Ho moments, Mn spins, and ferroelectric polarization. The derived phase diagram is far more complex than previously assumed including reentrant phases, phase transitions with distinct thermal and field hysteresis, as well as several multicritical points. Magnetoelastic interactions introduce lattice anomalies at the magnetic phase transitions. The re-evaluation of the T-H phase diagram of HoMnO_3 is demanded.Comment: 12 pages, 3 figure

Magnetic Phase Diagrams of Multiferroic Hexagonal RMnO3 (R=Er, Yb, Tm, and Ho)

The magnetic phase diagrams of RMnO3 (R = Er, Yb, Tm, Ho) are investigated up to 14 Tesla via magnetic and dielectric measurements. The stability range of the AFM order below the Neel temperature of the studied RMnO3 extends to far higher magnetic fields than previously assumed. Magnetic irreversibility indicating the presence of a spontaneous magnetic moment is found near 50 K for R=Er, Yb, and Tm. At very low temperatures and low magnetic fields the phase boundary defined by the ordering of the rare earth moments is resolved. The sizable dielectric anomalies observed along all phase boundaries are evidence for strong spin-lattice coupling in the hexagonal RMnO3. In HoMnO3 the strong magnetoelastic distortions are investigated in more detail via magnetostriction experiments up to 14 Tesla. The results are discussed based on existing data on magnetic symmetries and the interactions between the Mn-spins, the rare earth moments, and the lattice.Comment: 23 pages, 16 figures, to be published in JMR's Aug. focus issue on multiferroic

Structural Anomalies at the Magnetic and Ferroelectric Transitions in RMn2O5RMn_2O_5 (R=Tb, Dy, Ho)

Strong anomalies of the thermal expansion coefficients at the magnetic and ferroelectric transitions have been detected in multiferroic $RMn_2O_5$. Their correlation with anomalies of the specific heat and the dielectric constant is discussed. The results provide evidence for the magnetic origin of the ferroelectricity mediated by strong spin-lattice coupling in the compounds. Neutron scattering data for $HoMn_2O_5$ indicate a spin reorientation at the two low-temperature phase transitions