Ground state and stability of the fractional plateau phase in metallic Shastry Sutherland system TmB4

We present a study of the ground state and stability of the fractional plateau phase FPP with M Msat 1 8 in the metallic Shastry Sutherland system TmB4. Magnetization M measurements show that the FPP states are thermodynamically stable when the sample is cooled in constant magnetic field from the paramagnetic phase to the ordered one at 2 K. On the other hand, after zero field cooling and subsequent magnetization these states appear to be of dynamic origin. In this case the FPP states are closely associated with the half plateau phase HPP, M Msat , mediate the HPP to the low field antiferromagnetic AF phase and depend on the thermodynamic history. Thus, in the same place of the phase diagram both, the stable and the metastable dynamic fractional plateau FP states, can be observed, depending on the way they are reached. In case of metastable FP states thermodynamic paths are identified that lead to very flat fractional plateaus in the FPP. Moreover, with a further decrease of magnetic field also the low field AF phase becomes influenced and exhibits a plateau of the order of 1 1000 Msa

Crystal field potential and short range order effects in inelastic neutron scattering, magnetization, and heat capacity of the cage glass compound HoB12

The strongly correlated system Ho11B12 with boron sublattice Jahn Teller instability and nanoscale electronic phase separation dynamic charge stripes was studied in detail by inelastic neutron scattering INS , magnetometry, and heat capacity measurements at temperatures in the range of 3 300 K. From the analysis of registered INS spectra, we determined parameters of the cubic crystal field CF at holmium sites B4 amp; 8722;0.333 meV and B6 amp; 8722;2.003 meV in Stevens notations , with an unconventional large ratio B6 B4 pointing to the dominant role of conduction electrons in the formation of a CF potential. The molecular field in the antiferromagnetic AFM state Bloc 1.75 0.1 T has been directly determined from the INS spectra together with short range order effects detected in the paramagnetic state. A comparison of measured magnetization in diluted Lu0.99Ho0.01B12 and concentrated HoB12 single crystals showed a strong suppression of Ho magnetic moments by AFM exchange interactions in holmium dodecaboride. To account explicitly for the short range AFM correlations, a self consistent holmium dimer model was developed that allowed us to reproduce successfully field and temperature variations of the magnetization and heat capacity in the cage glass phase of HoB12 in external magnetic field

Influence of Lu substitution on the frustrated antiferromagnetic system HoB12

In this contribution we present results of experimental investigations of the geometrically frustrated metallic antiferromagnet HoB12 with ordering temperature TN 7.4 K influenced by substitution of magnetic Ho atoms through nonmagnetic Lu ones. In this case, in Ho1 xLuxB12 solid solutions, both chemical pressure and magnetic dilution take place with increasing content of Lu which changes the properties of the system. Experimentally, measurements of heat capacity and electrical resistivity of these solid solutions were performed from room temperature down to milikelvin temperatures and in magnetic fields up to 9 T. This wide range of experimental conditions allowed us among other things to follow the change of magnetic ordering temperature with concentration x , i.e. to obtain the TN vs. x phase diagram. The received results show strong indications for the existence of a quantum critical point QCP close to xc amp; 8776; 0.9. This critical point separates the region of magnetic order starting with HoB12 for x 0 and the nonmagnetic region ending with superconducting LuB12 for x

Rotating magnetocaloric effect in TmB 4 A comparison between estimations based on heat capacity and magnetization measurements

We present a comparison of the rotating magnetocaloric effect R MCE carried out on TmB4, a strongly anisotropic magnetic system, which is based on the determination of the entropy S and entropy change amp; 916;S. Both quantities are determined using independent measurements of the heat capacity and the magnetization as a function of temperature and magnetic field. The comparison of these two approaches shows that estimates of the R MCE, in particular the estimate of the temperature difference amp; 916;T that occurs during sample rotation in magnetic field H, based on magnetization measurements which usually present a simpler and faster way to obtain the necessary data provide similar results to those obtained from detailed temperature dependencies of heat capacity. However, to take the advantage of magnetisation measurements it is necessary to make an approximation concerning heat capacity data. There one has to be careful and use the right approximation for the amp; 916;T estimate. In case of materials with a complex temperature dependence of the heat capacity common approach can lead to significant errors. Our results here suggest for the entropy calculation from magnetic data sets the following procedure first determine the zero field H amp; 8239; amp; 8239;0 contribution to S from heat capacity data, then add to this the magnetic entropy change contribution determined from magnetization measurement

Magnetic properties of the frustated fcc antiferromagnet HoB12 above and below TN

We have investigated the magnetic ordering of the frustrated fcc antiferromagnet HoB12. Below TN 7.4K antiferromagnetic order and a complex phase diagram is observed. Above TN neutron scattering experiments show strong diffuse scattering. The diffuse signal indicates strong correlations between the rare earth moments along the [111] direction well above TN. The behavior of this component resembles low dimensional magnets which are known to show long range order only at T 0. Close to TN correlations perpendicular to the [111] direction get relevant, they diverge towards TN. Thus we observe a complex ordering process where the frustration is lifted in steps. The experimental data and their interpretation is presented, some of the possible microscopic origins are discusse

Maltese Cross Anisotropy in Antiferromagnetic State of Metallic Ho0.5Lu0.5B12 with Dynamic Charge Stripes

The model fcc system Ho0.5Lu0.5B12with substitutional disorder of Ho Lu ions, dynamic charge stripes,and a complex AF ground state has been studied by magnetoresistance at low temperatures in magnetic field upto 80 kOe. For this non equilibrium AF metal the angularH amp; 966; Tmagnetic phase diagram in the form of a Maltesecross has been constructed experimentally for the first time. It was shown that the dramatic symmetry loweringof the AF ground state in this rare earth dodecaboride should be attributed to the redistribution of charge carriersinto dynamic charge stripes due to RKKY oscillations of the conduction electrons spin density. This redistributioncauses extraordinary changes in the indirect exchange interaction between magnetic moments of Ho3 ions andresults in the emergence of a number of various magnetic phases and phase transition

Suppression of indirect exchange and symmetry breaking in the antiferromagnetic metal HoB12 with dynamic charge stripes

Precise angle resolved magnetoresistance ARM measurements are applied to reveal the origin of symmetry lowering in electron transport and the emergence of a huge number of magnetic phases in the ground state of the antiferromagnetic metal HoB12 with fcc crystal structure. By analyzing the polar H amp; 952; amp; 981; magnetic phase diagrams of this compound reconstructed from the experimental ARM data, we argue that nonequilibrium electron density oscillations dynamic charge stripes are responsible for the suppression of the indirect Ruderman Kittel Kasuya Yosida exchange along the 110 directions between the nearest neighboring magnetic moments of Ho3 ions in this strongly correlated electron syste

The Rashba Splitting in SmB6

The present article highlights two aspects at the intersection between Rashba physics and topological matter. Topologically nontrivial matter has been in the focus for almost two decades. It depends strongly on spin orbit coupling but, in contrast to large parts of modern solid state physics, strong electron correlation does not play a major role. In this context, SmB6 has been suggested as the first topological insulator driven by strong electron correlation and the first topological Kondo insulator. We review the important role of the Rashba splitting in determining that the observed surface states are not topological. Moreover, we point out that the Rashba splitting of SmB6 represents the extreme case of a large splitting in momentum space at a small Rashba paramete