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The magnetic properties of the MnRuxRh1-xAs system with x = 0.05, 0.10 were studied under hydrostatic pressure up to 1.2 GPa in the 80–420 K temperature range. The (p,T) magnetic phase diagram was determined. The ferromagnetic component in an intermediate (AF2+f) domain was stabilized with pressure for both samples, and the critical field variation versus pressure was determined. In addition, dc magnetization measurements were performed in magnetic fields up to 10 T, and the magnetic field–induced phase transitions were pointed out. The reverse and conventional magnetocaloric effect for both compounds was analyzed. Electronic band structure computations for the MnRuAs and MnRhAs parent compounds were performed by using the Korringa–Kohn-Rostoker method. The results indicate that significant changes of electronic states in the vicinity of EF on the application of external pressure tend to favor a ferromagnetic-type ordering of the Mn magnetic moments.

The crystal structure of MnRu x Rh 1-x As system belongs to the hexagonal Fe 2 P-type structure (SG: P 6 2m). Mn atoms locate at pyramidal (3g) sites, Ru and Rh atoms occupy tetrahedral (3f) sites and As atoms occupy 1b and 2c positions. Systematic XRD data collected in the 80 - 550 K temperature range and crystal structure refinements were performed for 0.05 < x < 1. From the thermal behavior of both the cell parameters and the atomic positions, a global analysis of the magneto-elastic characteristics was made. In this report we present the magnetocaloric characteristics (MCE), addressed to the Mn magnetic ordering. Both conventional (0.8

Molecular epidemiology uses genetic information from bacterial isolates to shed light on the population structure and dynamics of pathogens. Bacterial pathogens can now be studied by whole genome sequencing, but for some well-studied pathogens such as Mycobacterium tuberculosis a wealth of information is also available from other sources such as spoligotyping and multi-locus variable-number-tandem-repeats (VNTR). Isolates are also frequently tested for susceptibility to antibiotics. Methods of analysis are available for each type of data but it would be informative to combine multiple sources of information into a single analysis or visualisation. Here, we propose and implement a simple way to visualise genotypes along with drug resistance profiles for multiple drugs. We also present a way to combine information from different markers to aid in visualising relationships among isolates. These methods help to reveal the origins and spread of multi-drug resistant lineages of pathogens. We introduce a new computational package, MERCAT (Molecular Epidemiology Researcher's Collection of Analytical Tools), for analysing genotypic data from bacterial isolates. The software is available as an open source package in the statistical language R with a user-friendly interface using R Shiny. Although we focus on tuberculosis and the major molecular markers used to understand tuberculosis transmission – multilocus VNTR-typing (MLVA or MIRU) and spoligotyping – the methods and tools can be applied to other bacteria and can be easily tailored to other genetic markers such as SNP data from whole genome sequencing.

In this review paper comparison of magnetic properties in several MM’X-type intermetallics is presented. It may be summarized that main role in variation of magnetic interactions is played by modification of metallic sublattice in the tetrahedral but not in the pyramidal sites. It was shown not only in the case of composition, temperature and magnetic field dependencies but also by pressure variation of magnetic interactions. The latter was confirmed especially by electronic band structure calculations. Finally, in this report spin component and orbital one of magnetic moments for CoMnGe is presented for the first time.

In this report a review of magnetic properties of two groups of intermetallic compounds in relation with their magnetocaloric effect properties is presented. A first group of materials concerns the MM’X type (M, M’-metal 3d or 4d, X = As, P, Ge) of compounds. In this group the MnRh1-xCoxAs and MnFe1-xCoxP series of solid solutions are investigated. In a second group of materials, the Mn1-xTxAs (T = Cr, V, Ti, (Ti0.5V0.5) ) series of compounds are analyzed. In this case a special attention is paid for high dc field magnetization measurements and for selected compounds. As a summary the magnetic entropy change vs. M, M’ or T transition metal concentration for F-P phase transitions will be shown. Furthermore results of KKR-CPA electronic band structure computations in relation to magnetic properties are discussed.

The series of Mn2−xFexP1−ySiy types of compounds form one of the most promising families of magnetocaloric materials in term of performances and availability of the elemental components. Potential for large scale application needs to optimize the synthesis process, and an easy and rather fast process here described is based on the use of two main type of precursors, providing the Fe-P and Mn-Si proportions. The series of Mn2−xFexP1−ySiy compounds were synthesized and carefully investigated for their crystal structure versus temperature and compared interestingly with earlier results. A strong magnetoelastic effect accompanying the 1st order magnetic transition—as well as the parent phosphide–arsenides—was related to the relative stability of both the Fe magnetic polarization and the Fe–Fe exchange couplings. In order to better understand this effect, we propose a local distortion index of the non-metal tetrahedron hosting Fe atoms. Besides, from Mn-rich (Si-rich) to Fe-rich (P-rich) compositions, it is shown that the magnetocaloric phenomenon can be established on demand below and above room temperature. Excellent performance compounds were realized in terms of magnetic entropy ΔSm and adiabatic temperature ΔTad variations. Since from literature it was seen that the magnetic performances are very sensitive to the synthesis process, correspondingly here a new effective process is proposed. Mössbauer spectroscopy analysis was performed on Mn-rich, equi-atomic Mn-Fe, and Fe-rich compounds, allowing determination of the distribution of hyperfine fields setting on Fe in the tetrahedral and pyramidal sites, respectively. Electronic structure calculations confirmed the scheme of metal and non-metal preferential ordering, respectively. Moreover, the local magnetic moments were derived, in fair agreement with both the experimental magnetization and the Fe contributions, as determined by Mössbauer spectroscopy.

We provide a detailed physical discussion of the existence of a quantum critical point (QCP) at the metallization threshold of an almost stoichiometric magnetite, with the critical pressure p c = 8 GPa . A presence of an additional crossover or a critical line separating metallic and semiconducting states is proposed. A connection of the critical behavior to that of a spinless-fermion model with coupling of fermions to the lattice distortion is outlined.

The character of thermal diffusion of magnetic atoms has been investigated in Ni–Mn mechanical alloys around Ni3Mn composition by monitoring magnetic properties during the atomic ordering process. Observed susceptibility versus temperature curve after annealed at the ordering temperature of 693 K for 50 h shows at least four steps. Those multi steps came into two at the final stage of annealing for 1000 h. The step at the highest temperature corresponds to the Curie temperature TC of Ni3Mn. The observed variation of TC with annealed time was explained by solving a diffusion equation, and the range of the concentration fluctuation was determined to be 4 nm.

Both series of MnFe0.35−xCo0.65NixP and MnFe0.35Co0.65−xNixP orthorhombic compounds were analyzed for their structural characteristics versus x and versus temperature, as well for the changes induced to the magnetic behaviors (ordering temperature, saturation magnetization, magnetic entropy change). The operated Ni substitutions lead to decrease the Curie point closer to room temperature, especially when Ni substitutes to Co. However, in both systems, the saturation magnetization evolves unexpectedly. Even if remaining rather weak, the corresponding changes of magneto-caloric entropy at the transition are significantly increased, being more than twice and three times the initial value for Ni substituted to Fe and to Co respectively. Chemical and topological arguments are then proposed to discuss the noticeable difference of behaviors observed between the hexagonal (e.g. MnFeP1−xAsx) and the orthorhombic (e.g. MnFe1−xCoxP) series of polytype pnictides.

For the (Fe 1-x Ni x ) 2 P compounds with x = 0.015, 0.02, 0.025 and 0.25, both X-ray diffraction and X ac susceptibility experiments under pressure up to 1.5 GPa were performed from 80 to 420 K. For all the studied compounds, a clear cut metal atom distribution was found on the basis of the Fe 2 P structure-type (SG: P62m), the 3g sites being fully occupied by Fe, while both Fe and Ni are randomly distributed on the 3f sites. The variation of the ordering temperature under pressure ∂T C /∂p increases from negative values for all studied compounds up to zero for the Ni-rich one (Fe 0.75 Ni 0.25 ) 2 P. Additionally for the latter, neutron diffraction experiments were carried out in the 10-290 K range to characterise the transformation between the ferromagnetic (F) and paramagnetic (P) states. An electronic structure analysis of the (Fe 1-x Ni x ) 2 P compounds performed using the Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA) shows that the total energy calculation fully supports the Ni preference for the 3f occupancy. Accounting to this trend, the calculated total magnetic moment was found to decrease almost linearly with x, in very fair agreement with the experimental data when measured for x < 0.25. However, the theoretical values of local magnetic moments computed in (Fe 0.75 Ni 0.25 ) 2 P remain in satisfying agreement with the results of neutron diffraction. Hence, it is suggested that the strong electron polarisation at E F (P ∼ 90%) as established theoretically for the (Fe 1-x Ni x ) 2 P compounds having the smallest Ni content, can be responsible for the marked magneto-elastic phase transition as observed, e.g. in (Fe 0.975 Ni 0.025 ) 2 P.

The pressure dependence of the Curie temperatures of the Fe2P-type intermetallic compounds MnRhP, MnRhAs and MnRhAs0.6P0.4 was investigated up to 8 GPa. For MnRhAs both the Curie temperature TC and the temperature Tt of the transition from AFI to the canted state increased with pressure. However, Tt decreased abruptly at 5 GPa where a pressure-induced ferromagnetic transition was observed. In contrast, the rate of increase of TC increased substantially at this pressure. The large positive pressure dependence of TC in these compounds is found to be strongly related to the value of the lattice parameter c.

Measurements of the temperature dependence of the AC susceptibility were made for Fe–Ni Invar mechanical alloys under hydrostatic pressures up to 1.5 GPa. The Curie temperatures decreased linearly with pressure. The rate of decrease became larger for specimens annealed at higher temperatures. The temperature of annealing after ball milling has been directly related to the extent of the chemical concentration fluctuation, and the extent becomes smaller for specimens annealed at higher temperature. This tendency can be explained by assuming a Gaussian distribution function.

The magnetic properties and their pressure dependence in Fe 2 P-type quasi-ternary intermetallic compounds Mn(Rh 1− x Co x )As were investigated up to 8 GPa. The low temperature antiferromagnetic state AF(I) disappeared for x >0.2 and a new phase (Phase I) appeared with a small magnetic moment. The transition temperature T t2 from this phase to the canted state and the Curie temperature T c remained almost constant up to x =0.7. The pressure dependence of T t2 remained constant up to 3.5 GPa, and then Phase I disappeared above 4 GPa. On the other hand, T c increased with increasing pressure with a rate of 8 K/GPa up to 2–3 GPa and then with 22–25 K/GPa. This large increase in rate can be explained by considering an RKKY-type interaction between Mn–Mn atoms along the c -axis.

For (Co 1− x Mn x ) 2 P compounds ( x =0.6 and 0.65) both X-ray diffraction (from 100 to 420 K) and χ ac ( T ) and M T ( H ) measurements under pressure up to 1.5 GPa were analysed. The electronic structure was computed using the KKR–CPA method. Changing the Mn content from x =0.5–0.65 enhances significantly the DOS near the Fermi energy E F .

We report on the magnetic and magnetocaloric properties of a MnRhAs single crystal. The ternary arsenide exhibits a rather complex magnetic behaviour. A first order metamagnetic type transition from antiferromagnetic (AFI) to ferromagnetic (“F”) states takes place at TT ∼ 158 K, and a second order transition from F to AFII states occurs at TC ∼ 196 K, the paramagnetic state occurring at T > TN = 238 K. Magnetic entropy changes were calculated using, Maxwell relation, and Clausius-Clapeyron equation. Both approaches are compared and discussed. The AFI-F transition in MnRhAs gives rise to an interestingly high level of negative magnetocaloric effect. Under a field change 0-1 T, the maximum magnetic entropy variation is about 3 J/kg K. For sufficiently high enough magnetic fields, the magnetocaloric working temperature range below 158 K can be covered. The F-AFII transition is accompanied by a relatively modest magnetocaloric effect (−2.3 J/kg K for 5 T at TC = 196 K), but it improves the working temperature span as well as the magnetocaloric properties. A minimum estimated refrigerant capacity of about 900 J/kg can be provided by a MnRhAs single crystal compound.

Measurements of detailed magnetization curves have been made in a hexagonal Fe 2 P-type ternary intermetallic compound, MnRhP around the Curie temperature by using a sample-subtracting type magnetometer. For the critical exponents β =0.43 and δ =2.67 were obtained. Though this material is called nearly two-dimensional ferromagnet, the temperature dependence of the spontaneous magnetization determined from Arrott plots has no two-dimensional character. This tendency is different from the case of Cu 2 Sb-type intermetallic compounds, MnZnSb and MnGaGe in which two-dimensional character was observed in β .

We present new results on the crystal structure, magnetic and electronic properties of the Co x Fe 1− x MnP series of compounds. X-ray diffraction experiments were performed for x =0.525, x =0.65 and x =0.70. A jump both of the lattice parameters and the unit cell volume was evidenced at the metamagnetic phase transition between antiferromagnetic and ferromagnetic states. Moreover the ( P , T ) magnetic phase diagrams for x =0.45, x =0.50 and x =0.525 were determined. Mossbauer spectroscopy experiments were performed for several x contents allowing to determine the hyperfine field, the isomer shift and the quadrupole splitting of the iron sites. Spin-polarised electronic structure calculations were performed using the Korringa–Kohn–Rostoker (KKR) method both for CoMnP and FeMnP, in the ferromagnetic state. The calculated local magnetic moments are 0.25 μ B (Co), 2.90 μ B (Mn) and 0.83 μ B (Fe), 2.89 μ B (Mn) in CoMnP and FeMnP, respectively. The electronic structure of the Co x Fe 1− x MnP solid solutions ( x =0.525 and x =0.70) were calculated using the coherent potential approximation (CPA). The calculated values of the magnetic moments and hyperfine fields are compared with the experimental ones.

The magnetic properties of a Fe 2 P-type intermetallic compound MnRhAs have been investigated under high pressure up to 8.0 GPa by AC susceptibility measurement. Initially, both the antiferromagnetic (AF(I)) to the canted state magnetic transition temperature T t and the canted state to another antiferromagnetic one (AF(II)) transition temperature T C increase with compression. At 4.0 GPa, however, T t decreases abruptly, while the increasing rate of T C becomes larger above this pressure. A pressure-induced magnetic phase transition was seen at around this pressure when T t and T C are plotted in the pressure–temperature phase diagram. The transition from the antiferromagnetic to the ferromagnetic state observed below 160 K with increasing pressure is not frequently observed.

Pressure-induced structural transitions in MnRhP and MnRhAs were studied by in situ angle-dispersive X-ray diffraction using synchrotron radiation and a diamond anvil cell. A transition from a hexagonal Fe 2 P-type structure to an orthorhombic one was observed in MnRhP at a pressure of approximately 34 GPa. The first-nearest neighboring Mn–Mn interatomic distance at this transition pressure is close to the distance at which the sign of the effective exchange interaction coefficient between Mn atoms turns from positive to negative. A structural phase transition was also observed in MnRhAs at around 26 GPa, although the crystal system of the high-pressure phase was undetermined.

A newly developed pressure setup for a.c. susceptibility measurements in the pressure range up to 2.0 GPa is presented; the temperature domain extends from 77 to 450 K. The steel pressure chamber contains the sample located at the center of a set of three compensated pick-up coils and the pressure and temperature sensors. Either alcohol or extraction naphtha is used as the liquid pressure transmitting medium. The (P, T) magnetic phase diagram of (Fe0.975 Ni0.025 ) 2 Ρ system in the pressure range up to 2.0 GPa is reported. PACS numbers: 75.50.Cc, 07.55.Jg, 71.20.Lp

Measurements of detailed magnetization curves have been made in an orthorhombic TbFeSi2-type compound, LaMnSi2 around the Curie temperature by using a sample-subtracting type magnetometer. For the critical exponents, β = 0.33 and δ = 3.02 were obtained. Though this material is called nearly two-dimensional ferromagnet, the temperature dependence of the spontaneous magnetization determined from Arrott plots has no two-dimensional character. This tendency is different from the case of Cu2Sb-type intermetallic compounds, MnZnSb and MnGaGe in which two-dimensional character was observed in β.

The results of AC magnetic susceptibility measurements of zinc ferrite (Fe3−xZnxO4, x = 0, 0.0072, 0.0174, 0.049) single crystalline samples under pressure up to 1.2 GPa in the temperature range close to the Verwey transition temperature (TV) are reported. The isotropy point TIP increases with pressure for each x but the disappearance of primary anisotropy constant at TIP has no effect on Mossbauer spectrum at ambient pressure. Finally, Mossbauer effect data in the vicinity of the Verwey transition does not support the recent claim of the inverse to normal spinel crossover at the transition.

Summary The crystallographic and magnetic properties of Fe 2 P have been studied by neutron diffraction experiments, magnetization measurements and KKR method for band structure calculations. The measured atomic magnetic moments of tetrahedral Fe(3f) and pyramidal Fe(3g) sites are respectively (0.59±0.02)μ B and (2.22±0.01)μ B , resulting in a net moment of (2.82±0.03)μ B . This value is very close to that obtained from saturation magnetization measurements (H=150kOe, T=4K) which yield 2.87μ B per formula unit. The results obtained from the KKR method are 0.80, 2.33, −0.03(1), −0.02(8)μ B for Fe and P sites respectively. The values are comparable with the measured atomic magnetic moments. Thermal evolution of magnetic moments, magnetization at saturation and cell parameters presents a sharp drop at the Curie temperature (217±2)K indicating a first order ferro - paramagnetic transition.

In this review paper comparison of magnetic properties in several MM’X-type intermetallics is presented. It may be summarized that main role in variation of magnetic interactions is played by modification of metallic sublattice in the tetrahedral but not in the pyramidal sites. It was shown not only in the case of composition, temperature and magnetic field dependencies but also by pressure variation of magnetic interactions. The latter was confirmed especially by electronic band structure calculations. Finally, in this report spin component and orbital one of magnetic moments for CoMnGe is presented for the first time.

The Ce 2 Fe 17 H x ternary hydrides with x = 0.8 and 2 have been studied under external pressures up to 1.2 GPa in order to check the stability of H-induced ferromagnetism. The resulting T vs P phase diagrams allow valuable comparisons with the x vs. T ones if hydrogen ( x ) is assumed to act as a negative pressure tool.

In both the series of ternary d-metal pnictides MnFeP1 − xAsx and MnRhP1 − xAsx the magnetic properties appear to be very sensitive to external parameters (temperature, pressure, magnetic field) and chemical composition. An extended analysis of previous experimental results is discussed in relation to the magneto-elastic phase transition in view of band structure calculations. The principal trends of these experiments are presented here.

The magnetoelastic phase transitions were observed in MnRhAs1_ xPs system (space group P62m) by X-ray measurements (80 K < T < 300 K). For x = 0.33 and x = 0.4 contents an abrupt change of both lattice parameters and of the elementary cell volume at the metamagnetic transition was detected. The Korringa—Kohn—Rostoker electronic structure calculations performed for MnRhP compound show significant variations of densities of states at the Fermi level, while changing lattice data. The Korringa—KohnRostoker-coherent potential approximation studies of disordered MnRhAs1_xPx system (x = 0.6,0.8, 1.0) were done at the ferromagnetic region. From our calculations we observe moving of bands near EF, while substituting with isoelectronic metalloid, likely as while changing the crystal data in MnRhP. PACS numbers: 71.20.Lp, 71.20.—b, 75.50.Cc

We present results of the electronic structure study for the solid solu- tion (Fe1_xNi x )2P (space group P62m). The samples were synthesized for x = 0.0 up to 0.15. From the electrical conductivity measurements on these materials, it was verified that resistivity increases with increasing tempera- ture up to the Curie point Tc and changes the slope at Tc decreasing when temperature is raised above Tc. To get insight into the possible origin of such observations, we carried out the Korringa—Kohn—Rostoker-coherent poten- tial approximation electronic structure calculations for (Fe1_ x Ni x )2P in the

Magnetic susceptibility measurements of magnetite and zinc ferrite (Fe 3 - x Zn x O 4 , x = 0.0174 , 0.049) single-crystal samples were performed under pressure up to 1.2 GPa in the temperature range close to the Verwey transition T V . The application of pressure p decreases T V linearly. The χ AC signal is not affected above T V , but rises below T V with p; this was explained by increasing domain wall movement. Finally, the isotropy point T IP increases with pressure indicating that magnetism does not actively participate in the Verwey transition.

The magnetization at high magnetic field and the a.c. magnetic susceptibility of RAgSn (RNd, Tb and Ho), TbPdSn and TbAgGa polycrystalline samples have been measured. The temperature dependence of the magnetic susceptibility indicates an antiferromagnetic order at low temperatures. The magnetization curves for all compounds show a multistep metamagnetic process in an ordered state.

For the hexagonal phase FeMnP 1- x As x , neutron diffraction and Mossbauer spectroscopy results are compared. The magnetoelastic transition is accompanied by a drastic change in the 57 Fe hyperfine field that is more than twice as large in the ferro (F) than in the antiferromagnetic (AF) state. Such trends exist in FeMnX (X = As, P) and can be related to the changes in the FeFe distances.

A concept for disposal of immobilized nuclear fuel waste in a vault mined deep in stable plutonic rock of the Canadian Shield is being investigated in Canada. Far in the future, when man-made and natural protective barriers lose their integrity, radionuclides carried by groundwater may migrate from the vault to the biosphere. During this time, many transitional processes will cause changes to the climate, hydrogeology and surface features of the biosphere. Glaciation is the most severe transitional process and its impacts on the disposal concept must be assessed. Using a discrete-state approach, the effects of glaciation were evaluated by performing separate time-independent radiological dose assessments of interglacial and cold interstadial states assuming that each state persists throughout the entire simulation period of 100 000 years. We assume that humans will not inhabit a full glacial environment. One of the major glacial processes is increased runoff during melt. This should decrease nuclide concentrations and doses in the immediate discharge zone of the vault through flushing and dilution. Temperature and moisture fluctuations will have only a minor impact on nuclide transport in soils and surface waters. Our calculations show that it is unlikely that cold interstadial conditions will lead to substantially higher doses to humans resulting from radionuclides in the environment than the current interglacial state.