Magnetic order in 2D antiferromagnets disclosed by spontaneous anisotropic magnetostriction

The temperature dependent order parameter provides important information on the nature of magnetism. Using traditional methods to study this parameter in two-dimensional (2D) magnets remains difficult, however, particularly for insulating antiferromagnetic (AF) compounds. We show that its temperature dependence in AF MPS3 (M(II) = Fe, Co, Ni)...

Resonant optical control of magnetism on ultrashort timescales

Excitation of optical transitions in solids using ultrashort pulses of light allows to selectively perturb microscopic degrees of freedom in order to change and control material properties on very short timescales. In this thesis we study how ultrafast resonant excitation of optical transitions can induce coherent structural dynamics in wide...

Applied and fundamental studies of vibrating 2D membranes

This thesis encompasses both applied and fundamental studies of suspended van der Waals materials. Chapters 1 and 2 give an introduction to the field of 2D materials and some of the critical methods which facilitate the study of the suspended structures. In Chapters 3 and 4 we focus on the applications of graphene in barometric pressure sensors...

Structural and magnetic properties of hexagonal (Mn,Fe)_3-δGa

We have investigated the crystallographic and magnetic properties of (Mn,Fe)_3-δGa alloys. The hexagonal phase is stable between 600 and 700 °C and can be stabilized by quenching to room temperature. Mn₃Ga is reported to be off-stoichiometric, but we show that using melt-spinning the stoichiometric compound is attainable....

From single- to double-first-order magnetic phase transition in magnetocaloric Mn1−xCrxCoGe compounds

Substitution of some Cr for Mn atoms in MnCoGe was employed to control the magnetic and structural transitions in this alloy to coincide, leading to a single first-order magnetostructural transition from the ferromagnetic to the paramagnetic state with a giant magnetocaloric effect observed near room temperature. Further increase in the Cr...

Magnetic ordering in the spinel compound Li[Mn2?xLix]O4(x = 0,0.04)

The two B-site ions Mn3+ and Mn4+ in the stoichiometric spinel structure LiMn2O4 form a complex, columnar ordered pattern below the charge-ordering transition at room temperature. On further cooling to below 66 K, the system develops long-range antiferromagnetic order. In contrast, whereas lithium-substituted Li[Mn2?xLix]O4 also undergoes a...

Microstructures and the corresponding magnetic properties of half-doped Nd0.5Sr0.5MnO3 films

The microstructural and magnetic properties of amorphous, nanoclustered, and self-organized bilayer Nd0.5Sr0.5MnO3 films, prepared by rf magnetron sputtering, are investigated. The amorphous film was found to be a typical paramagnet with free motion of the individual Mn spins, and the magnetic properties are well described on the basis of the...

Magnetic order in the two-dimensional randomly mixed ferromagnet-antiferromagnet Rb2Cu1-xCoxF4

Breakup of long-range order in the diluted antiferromagnet K2MnxZn1-xF4 in zero magnetic field

NMR study of local magnetizations in diluted two-dimensional antiferromagnets

Monte Carlo investigation of diluted antiferromagnets in high magnetic fields