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

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matúš Orendáč ◽  
Slavomír Gabáni ◽  
Pavol Farkašovský ◽  
Emil Gažo ◽  
Jozef Kačmarčík ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Ground State ◽  
Constant Magnetic Field ◽  
Paramagnetic Phase ◽  
The Other ◽  
Zero Field ◽  
Plateau Phase ◽  
Low Field ◽  
Zero Field Cooling

AbstractWe 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 = ½), 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 Msat.

scholarly journals Chip-Scale Ultra-Low Field Atomic Magnetometer Based on Coherent Population Trapping

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1517
Author(s):  
Hyun-Gue Hong ◽  
Sang Eon Park ◽  
Sang-Bum Lee ◽  
Myoung-Sun Heo ◽  
Jongcheol Park ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ground State ◽  
Coherent Population Trapping ◽  
Zero Magnetic Field ◽  
Zero Field ◽  
Resonance Signal ◽  
Low Field ◽  
Low Magnetic Field ◽  
Population Trapping ◽  
Wide Operating

We report a chip-scale atomic magnetometer based on coherent population trapping, which can operate near zero magnetic field. By exploiting the asymmetric population among magnetic sublevels in the hyperfine ground state of cesium, we observe that the resonance signal acquires sensitivity to magnetic field in spite of degeneracy. A dispersive signal for magnetic field discrimination is obtained near-zero-field as well as for finite fields (tens of micro-tesla) in a chip-scale device of 0.94 cm3 volume. This shows that it can be readily used in low magnetic field environments, which have been inaccessible so far in miniaturized atomic magnetometers based on coherent population trapping. The measured noise floor of 300 pT/Hz1/2 at the zero-field condition is comparable to that of the conventional finite-field measurement obtained under the same conditions. This work suggests a way to implement integrated atomic magnetometers with a wide operating range.

scholarly journals Asymptotic Growth of the Local Ground-State Entropy of the Ideal Fermi Gas in a Constant Magnetic Field

2020 ◽  
Author(s):  
Hajo Leschke ◽  
Alexander V. Sobolev ◽  
Wolfgang Spitzer
Keyword(s):  
Magnetic Field ◽  
Ground State ◽  
Constant Magnetic Field ◽  
Chemical Potential ◽  
Fermi Gas ◽  
Von Neumann Entropy ◽  
Zero Field ◽  
Quantum Gas ◽  
Asymptotic Growth ◽  
The Ideal

AbstractWe consider the ideal Fermi gas of indistinguishable particles without spin but with electric charge, confined to a Euclidean plane $${{\mathbb {R}}}^2$$ R 2 perpendicular to an external constant magnetic field of strength $$B>0$$ B > 0 . We assume this (infinite) quantum gas to be in thermal equilibrium at zero temperature, that is, in its ground state with chemical potential $$\mu \ge B$$ μ ≥ B (in suitable physical units). For this (pure) state we define its local entropy $$S(\Lambda )$$ S ( Λ ) associated with a bounded (sub)region $$\Lambda \subset {{\mathbb {R}}}^2$$ Λ ⊂ R 2 as the von Neumann entropy of the (mixed) local substate obtained by reducing the infinite-area ground state to this region $$\Lambda $$ Λ of finite area $$|\Lambda |$$ | Λ | . In this setting we prove that the leading asymptotic growth of $$S(L\Lambda )$$ S ( L Λ ) , as the dimensionless scaling parameter $$L>0$$ L > 0 tends to infinity, has the form $$L\sqrt{B}|\partial \Lambda |$$ L B | ∂ Λ | up to a precisely given (positive multiplicative) coefficient which is independent of $$\Lambda $$ Λ and dependent on B and $$\mu $$ μ only through the integer part of $$(\mu /B-1)/2$$ ( μ / B - 1 ) / 2 . Here we have assumed the boundary curve $$\partial \Lambda $$ ∂ Λ of $$\Lambda $$ Λ to be sufficiently smooth which, in particular, ensures that its arc length $$|\partial \Lambda |$$ | ∂ Λ | is well-defined. This result is in agreement with a so-called area-law scaling (for two spatial dimensions). It contrasts the zero-field case $$B=0$$ B = 0 , where an additional logarithmic factor $$\ln (L)$$ ln ( L ) is known to be present. We also have a similar result, with a slightly more explicit coefficient, for the simpler situation where the underlying single-particle Hamiltonian, known as the Landau Hamiltonian, is restricted from its natural Hilbert space $$\text{ L}^2({{\mathbb {R}}}^2)$$ L 2 ( R 2 ) to the eigenspace of a single but arbitrary Landau level. Both results extend to the whole one-parameter family of quantum Rényi entropies. As opposed to the case $$B=0$$ B = 0 , the corresponding asymptotic coefficients depend on the Rényi index in a non-trivial way.

scholarly journals Vortex phase diagram and the normal state of cuprates with charge and spin orders

2020 ◽  
Vol 6 (7) ◽  
pp. eaay8946 ◽  
Author(s):  
Zhenzhong Shi ◽  
P. G. Baity ◽  
T. Sasagawa ◽  
Dragana Popović
Keyword(s):  
Phase Diagram ◽  
Normal State ◽  
Ground State ◽  
High Field ◽  
High Temperature Superconductors ◽  
Upper Critical Field ◽  
Energy Scale ◽  
Zero Field ◽  
Vortex Matter ◽  
Nonlinear Transport

The phase diagram of underdoped cuprates in a magnetic field (H) is key to understanding the anomalous normal state of these high-temperature superconductors. However, the upper critical field (Hc2), the extent of superconducting (SC) phase with vortices, and the role of charge orders at high H remain controversial. Here we study stripe-ordered La-214, i.e., cuprates in which charge orders are most pronounced and zero-field SC transition temperatures Tc0 are lowest. This enables us to explore the vortex phases in a previously inaccessible energy scale window. By combining linear and nonlinear transport techniques sensitive to vortex matter, we determine the T − H phase diagram, directly detect Hc2, and reveal novel properties of the high-field ground state. Our results demonstrate that quantum fluctuations and disorder play a key role as T → 0, while the high-field ground state is likely a metal, not an insulator, due to the presence of stripes.

Half-Integer Spin Molecular Nanomagnets

2002 ◽  
Vol 746 ◽  
Author(s):  
David N. Hendrickson ◽  
George Christou ◽  
Wolfgang Wernsdorfer ◽  
Stephen O. Hill ◽  
Núria Aliaga-Alcade ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Exchange Interaction ◽  
Single Molecule ◽  
Ground State ◽  
Exchange Interactions ◽  
Transverse Component ◽  
Zero Field ◽  
Magnetic Exchange ◽  
Integer Spin ◽  
Half Integer

ABSTRACTSingle-molecule magnets (SMM) are molecules that function as single-domain nanomagnets. SMMs have been characterized with a ground-state spin ranging from S = 4 to S = 13. A few SMMs have been identified that have half-integer spin ground states. [Cation][Mn12O12(O2CR)16(H2O)4] complexes, where R is some substituent, are SMMs that have either a S = 19/2 or 21/2 ground state. Quantum tunneling of magnetization (QTM) is observed for these half-integer-spin Kramers [Mn12]- degenerate SMMs in zero external magnetic field, as well as for a class of S = 9/2 Mn4 SMMs. The presence of QTM in zero external field is attributed to a transverse component of a nuclear spin field, dipolar interactions and intermolecular exchange interactions. The Landau-Zener method is used to measure the tunnel splitting as a function of transverse magnetic field for a single crystal of the S = 9/2 SMM [Mn4O3(OSiMe3)(OAc)3(dbm)3]. Spin parity dependent QTM is established. The effect of a magnetic exchange interaction between two S = 9/2 Mn4 SMMs upon QTM was studied for another compound. The hydrogen bonding and Cl…Cl contacts within a supramolecularly linked [Mn4]2 dimer lead to a weak antiferromagnetic exchange interaction between the two S = 9/2 SMMs. This interaction causes a shift (exchange bias) from zero field for the magnetic field at which QTM occurs.

ON SPECTRAL AND SCATTERING THEORY FOR N-BODY, SCHRÖDINGER OPERATORS IN A CONSTANT MAGNETIC FIELD

2002 ◽  
Vol 14 (02) ◽  
pp. 199-240 ◽  
Author(s):  
TADAYOSHI ADACHI
Keyword(s):  
Magnetic Field ◽  
Constant Magnetic Field ◽  
Scattering Theory ◽  
Short Range ◽  
Asymptotic Completeness ◽  
The Other ◽  
Conjugate Operator ◽  
Neutral Particles ◽  
Pair Potentials ◽  
Spectral And Scattering Theory

We consider an N-body quantum system in a constant magnetic field which consists of just one charged and the other N - 1 neutral particles. We prove the existence of a conjugate operator for the Hamiltonian which governs the system, and show the asymptotic completeness of the system under short-range assumptions on the pair potentials.

Extended Vacuum Solutions and their Elementary Excitations of the Yang–Mills Gauge Theory

1997 ◽  
Vol 12 (27) ◽  
pp. 2037-2045
Author(s):  
T. Tajima ◽  
Q. Niu
Keyword(s):  
Magnetic Field ◽  
Gauge Theory ◽  
Constant Magnetic Field ◽  
Vacuum Solution ◽  
Landau Levels ◽  
The Other ◽  
Elementary Excitations ◽  
Circularly Polarized ◽  
Yang Mills ◽  
Vacuum Solutions

A number of nontrivial vacua of the Yang–Mills gauge theory which are extended in space are derived. For the vacuum solution with a constant "magnetic" field of one color species, the elementary excitations of the other species are circularly polarized, with a spectrum much like the Landau levels of nonrelativistic electrons in a constant magnetic field.

scholarly journals Analog Video Magnetograms in Real Time

1971 ◽  
Vol 43 ◽  
pp. 76-83 ◽  
Author(s):  
R. C. Smithson ◽  
R. B. Leighton
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Magnetic Field ◽  
Solar Spectrum ◽  
Zeeman Splitting ◽  
The Other ◽  
Line Of Sight ◽  
Zero Field ◽  
The Sun ◽  
Solar Magnetic Fields

For many years solar magnetic fields have been measured by a variety of techniques, all of which exploit the Zeeman splitting of lines in the solar spectrum. One of these techniques (Leighton, 1959) involves a photographic subtraction of two monochromatic images to produce a picture of the Sun in which the line-of-sight component of the solar magnetic field appears as various shades of gray. In a magnetogram made by this method, zero field strength appears as neutral gray, while magnetic fields of one polarity or the other appear as lighter or darker areas, respectively. Figure 1 shows such a magnetogram.

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