For a class of frustrated spin lattices including the Kagomé lattice we construct exact eigenstates consisting several independent, localized one-magnon states and argue that they are ground for high magnetic fields. If maximal number local magnons scales with spins in system, which is case lattice, effect persists thermodynamic limit gives rise to macroscopic jump zero-temperature magnetization curve just below saturation field. The decreases increasing quantum vanishes classical limit....

The time-dependent variational principle for many-body trial states is used to discuss the relation between approaches of different molecular-dynamics models that describe indistinguishable fermions. Early attempts include effects Pauli by means nonlocal potentials, as well more recent work with antisymmetrized states, are reviewed under these premises.

Playing it cool: Almost all of the constituent parts complex [LnIII4MII8(OH)8(L)8(O2CR)8]X4, namely lanthanide ions Ln3+, transition-metal M2+, bridging ligand L, carboxylates, and counterions X can be exchanged, thus allowing a thorough understanding individual contributions to magnetocaloric effect. Example in picture: Gd purple, Cu green, O red, N blue. Detailed facts importance specialist readers are published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited...

In magnetism, of which molecular magnetism is a part, the term frustration used rather sloppily. Sometimes one gains impression that if reason for some phenomenon not quite clear then it attributed to frustration. this paper discussion effects are relevant field presented. As will become later these indeed lead variety unusual magnetic properties.

Abstract Geometric spin frustration in low-dimensional materials, such as the two-dimensional kagome or triangular antiferromagnetic nets, can significantly enhance change of magnetic entropy and adiabatic temperature following a applied field, that is, magnetocaloric effect. In principle, an equivalent outcome should also be observable certain high-symmetry zero-dimensional, molecular, structures with frustrated topologies. Here we report experimental realization this heptametallic...

Abstract The cyclisation of a short chain into ring provides fascinating scenarios in terms transforming finite array spins quasi-infinite structure. If frustration is present, theory predicts interesting quantum critical points, where the ground state and thus low-temperature properties material change drastically upon even small variation appropriate external parameters. This can be visualised as achieving very high pointed summit way down has an infinity possibilities, which by any...

For the paradigmatic frustrated spin-half Heisenberg antiferromagnet on kagome lattice we performed large-scale numerical investigations of thermodynamic functions by means finite-temperature Lanczos method for system sizes up to $N=42$. We present dependence magnetization as well specific heat temperature and external field show in particular that a finite-size scaling supports appearance low-temperature shoulder below major maximum. This seems be result counterintuitive motion density...

Reaction of Gd(OAc)3·4H2O, salicylaldehyde and CH3ONa in MeCN/MeOH affords [Gd12Na6(OAc)25(HCO2)5(CO3)6(H2O)12]·9H2O.0.5MeCN (1·9H2O.0.5MeCN), whose structure describes a quadruple-wheel consisting two {Na3} {Gd6} rings. The magnetic properties 1 reveal very weak antiferromagnetic interactions between the GdIII ions, which give rise to record magnetocaloric effect at low applied fields temperatures. entropy change reaches -ΔSm= 29.3 J kg-1 K-1 for full demagnetization from B = T 0.5 K.

Complementary theoretical modeling methods are presented for the classical and quantum Heisenberg model to explain magnetic properties of nanometer-sized molecules. Excellent quantitative agreement is achieved between our experimental data down 0.1 K fields up 60 Tesla results giant Keplerate species {Mo72Fe30}, by far largest paramagnetic molecule synthesized date.

We investigate the magnetocaloric properties of certain antiferromagnetic spin systems that have already been or very likely can be synthesized as magnetic molecules. It turns out special geometric frustration which is present in antiferromagnets consist corner-sharing triangles leads to an enhanced effect with high cooling rates vicinity saturation field. These findings are compared behavior a simple unfrustrated ring well icosahedron. To our surprise, also for icosahedron large achieved...

The authors investigate approximations of the partition function that can be used for large systems where an exact evaluation is impossible. These methods rest on observation traces replaced by expectation values with respect to a single random vector not too small temperatures. At low temperatures, vectors produce strongly fluctuating approximations, proper average over many yields quasi results.

In an effort to understand the low-temperature behavior of recently synthesized molecular magnets, we present numerical evidence for existence a rotational band in systems quantum spins interacting with nearest-neighbor antiferromagnetic Heisenberg exchange. While this result has previously been noted ring arrays even number spin sites, find that it also applies rings odd sites as well all polytope configurations have investigated (tetrahedron, cube, octahedron, icosahedron, triangular...

For a class of frustrated spin lattices including for example the 1D sawtooth chain, 2D Kagomé and checkerboard, as well 3D pyrochlore lattices, we construct exact product eigenstates consisting several independent, localized one-magnon states in ferromagnetic background. Important geometrical elements relevant are triangles being attached to polygons or lines. Then magnons can be trapped on these polygons/lines. If concentration is small, they distributed randomly over lattice. On...

Three heterometallic cluster complexes {Ln(12)Mo(4)} featuring an Ln(12) core of a distorted truncated tetrahedron were synthesized with the assistance four MoO(4)(2-) anions as ancillary ligands. Magnetic studies {Gd(12)Mo(4)} revealed large magnetocaloric effect due to presence number weakly coupled Gd(III) ions.

Reaction of [Fe3(μ3-O)(O2C(t)Bu)6(HO2C(t)Bu)3](O2C(t)Bu) and [Ln2(O2C(t)Bu)6(HO2C(t)Bu)6] (Ln = lanthanide) with three different phosphonic acids produce a family highly symmetrical {Fe6Ln6P6} clusters general formula [Fe6Ln6(μ3-O)2(CO3)(O3PR)6(O2C(t)Bu)18], where R methyl 1, phenyl 2, or n-hexyl 3. All the present an analogous metal frame to previously reported {Ni6Ln6P6} both being related well-known Wells-Dawson ion from polyoxometallate chemistry. These have, approximate very closely to,...

We report the synthesis and structure of a molecular {Gd7} cage formula (iPr2NH2)6[Gd7(μ3-OH)3(CO3)6(O2C t Bu)12] which has crystallographic C3h symmetry. Low temperature specific heat adiabatic demagnetization experiments (the latter achieving temperatures below 100 mK), lead to observation effects both intramolecular dipolar interactions geometric spin frustration. The interaction leads massive rearrangement energy levels such that entropy 2 K are strongly modified while magnetic...

Magnetic molecules are zero-dimensional quantum spin objects. This article is devoted to the general scientific knowledge we obtained through their study. In particular following concepts will be touched: anisotropy and bistability, translational invariance sign rules, frustration, localised magnons flat bands, phase transitions as well isentrope design.

Cyclic coordination clusters (CCCs) are proving to provide an extra dimension in terms of exotic magnetic behavior as a result their finite but cyclized chain structures. The Fe18Dy6 CCC is Single Molecule Magnet with the highest nuclearity among Ln containing clusters. three isostructural compounds [Fe18Ln6(μ-OH)6(ampd)12(Hampd)12(PhCO2)24](NO3)6·38MeCN for = DyIII (1), LuIII (2), or YIII (3), where H2ampd 2-amino-2-methyl-1,3-propanediol, reported. These can be described cyclization six...

Over the last decade, interest in spin-$1/2$ Heisenberg antiferromagnet (HAF) on square-kagome (also called shuriken) lattice has been growing as a model system of quantum magnetism with paramagnetic ground state, flat-band physics near saturation field, and scars. Here, we present large-scale numerical investigations specific heat $C(T)$, entropy $S(T)$ well susceptibility $\chi(T)$ by means finite-temperature Lanczos method for sizes $N=18,24,30,36,42,48$, $N=54$. We find that exhibits...

We report the magnetic features of a one-dimensional stack antiferromagnetically coupled equilateral copper(II) triangles. High-field magnetization measurements show that interaction between copper triangles is same order magnitude as intratriangle exchange although only via hydrogen bonds. The infinite chain turns out to be an interesting example frustrated cylindrical three-leg ladder with competing intra- and inter-triangle interactions. demonstrate ground state spin singlet which gaped...

We identify a class of zero-dimensional classical and quantum Heisenberg spin systems exhibiting anomalous behavior in an external magnetic field $B$ similar to that found for the geometrically frustrated kagome lattice spins. Our calculations isotropic model show emergence pronounced minimum differential susceptibility $dM/dB$ at ${B}_{\mathrm{s}\mathrm{a}\mathrm{t}}/3$ as temperature $T$ is raised from 0 K structures based on corner-sharing triangles, specifically octahedron,...