Metamagnetism

About: Metamagnetism is a research topic. Over the lifetime, 2023 publications have been published within this topic receiving 38108 citations.

Quenched-disorder-induced magnetization jumps in (Sm,Sr)MnO3

Abstract: Magnetic field induced steplike changes in magnetization and resistivity of ${\mathrm{Sm}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ manganites were studied. A strong dependence of these features on the cooling rate was observed. Magnetostriction, however, does not show the presence of large strain in our samples. From all these features we can rule out the conventional explanation of magnetization jumps as a consequence of martensitic transition. We propose instead that quenched by fast cooling disorder leads to the formation of an inhomogeneous metastable state and to subsequent magnetization jumps.

Magnetic Properties of Rare Earth Copper Intermetallic Compounds, RCu 2 . II. Light Rare Earth

Abstract: Measurements of magnetization and susceptibility have been made on single crystals of heavy rare earth copper compounds, RCu 2 . All these compounds show metamagnetism with a relative low critical field at 4.2 K. The paramagnetic Curie temperatures along each principal axis are anisotropic. The crystal field parameters V 2 0 and V 2 2 are determined from the values of anisotropic paramagnetic Curie temperatures on the basis of the molecular field theory. These values are in agreement with those evaluated from a point charge model. The neutron diffraction measurements on a TbCu 2 single crystal confirm the collinear magnetic structure.

Holographic metamagnetism, quantum criticality, and crossover behavior

Abstract: Using high-precision numerical analysis, we show that 3+1 dimensional gauge theories holographically dual to 4 + 1 dimensional Einstein-Maxwell-Chern-Simons theory undergo a quantum phase transition in the presence of a finite charge density and magnetic field. The quantum critical theory has dynamical scaling exponent z = 3, and is reached by tuning a relevant operator of scaling dimension 2. For magnetic field B above the critical value B c , the system behaves as a Fermi liquid. As the magnetic field approaches B c from the high field side, the specific heat coefficient diverges as 1/(B - B c ), and non-Fermi liquid behavior sets in. For B < B c the entropy density s becomes non-vanishing at zero temperature, and scales according to $$ s \sim \sqrt {{B_c} - B} $$ . At B = B c , and for small non-zero temperature T, a new scaling law sets in for which s ∼ T 1/3. Throughout a small region surrounding the quantum critical point, the ratio s/T 1/3 is given by a universal scaling function which depends only on the ratio (B - B c )/T 2/3. The quantum phase transition involves non-analytic behavior of the specific heat and magnetization but no change of symmetry. Above the critical field, our numerical results are consistent with those predicted by the Hertz/Millis theory applied to metamagnetic quantum phase transitions, which also describe non-analytic changes in magnetization without change of symmetry. Such transitions have been the subject of much experimental investigation recently, especially in the compound Sr3Ru2O7, and we comment on the connections.

Roles of critical valence fluctuations in Ce- and Yb-based heavy fermion metals.

Abstract: The roles of critical valence fluctuations of Ce and Yb are discussed as a key origin of several anomalies observed in Ce- and Yb-based heavy fermion systems. Recent development of the theory has revealed that a magnetic field is an efficient control parameter to induce the critical end point of the first-order valence transition. Metamagnetism and non-Fermi liquid behavior caused by this mechanism are discussed by comparing favorably with CeIrIn5, YbAgCu4 and YbIr2Zn20. The interplay of the magnetic order and valence fluctuations offers a key concept for understanding Ce- and Yb-based systems. It is shown that suppression of the magnetic order by enhanced valence fluctuations gives rise to the coincidence of the magnetic-transition point and valence crossover point at absolute zero as a function of pressure or magnetic field. The interplay is shown to resolve the outstanding puzzle in CeRhIn5 in a unified way. The broader applicability of this newly clarified mechanism is discussed by surveying promising materials such as YbAuCu4, β-YbAlB4 and YbRh2Si2.

High-field phase diagram of the heavy-fermion metal YbRh2Si2

Abstract: The tetragonal heavy-fermion (HF) metal YbRh2Si2 (Kondo temperature TK≈ 25 K) exhibits a magnetic field-induced quantum critical point related to the suppression of very weak antiferromagnetic (AF) ordering (TN = 70 mK) at a critical field of Bc = 0.06 T (B⊥ c). To understand the influence of magnetic fields on quantum criticality and the Kondo effect, we study the evolution of various thermodynamic and magnetic properties upon tuning the system by magnetic field. At B > Bc, the AF component of the quantum critical fluctuations becomes suppressed, and FM fluctuations dominate. Their polarization with magnetic field gives rise to a large increase of the magnetization. At B* = 10 T, the Zeeman energy becomes comparable to kB TK, and a steplike decrease of the quasi-particle mass deduced from the specific-heat coefficient indicates the suppression of HF behaviour. The magnetization M(B) shows a pronounced decrease in slope at B* without any signature of metamagnetism. The field dependence of the linear magnetostriction coefficient suggests an increase of the Yb-valency with field, reaching 3+ at high fields. A negative hydrostatic pressure dependence of B* is found, similar to that of the Kondo temperature. We also compare the magnetization behaviour in pulsed fields up to 50 T with that of the isoelectronic HF system YbIr2Si2, which, due to a larger unit-cell volume, has an enhanced TK of about 40 K.