New Materials and Effects in Molecular Nanomagnets

Abstract

Molecular magnets are a relatively new class of purely organic or metallo-organic materials, showing magnetism even without an external magnetic field. This interdisciplinary field between chemistry and physics has been gaining increased interest since the 1990s. While bulk molecular magnets are usually hard to build because of their molecular structures, low-dimensional molecular magnets are often easier to construct, down to dot-like (zero-dimensional) structures, which are investigated by different scanning probe technologies. On these scales, new effects such as superparamagnetic behavior or coherent switching during magnetization reversal can be recognized. Here, we give an overview of the recent advances in molecular nanomagnets, starting with single-molecule magnets (0D), typically based on Mn12, Fe8, or Mn4, going further to single-chain magnets (1D) and finally higher-dimensional molecular nanomagnets. This review does not aim to give a comprehensive overview of all research fields dealing with molecular nanomagnets, but instead aims at pointing out diverse possible materials and effects in order to stimulate new research in this broad field of nanomagnetism.

Heterometallic 3d–4f Alkoxide Precursors for the Synthesis of Binary Oxide Nanomaterials

“…2−4 The first example of a 3d−4f SMM was [CuTb(hfac) 2 (L)] 2 (H 3 L = 1-(2-hydroxybenzamido)-2-(2hydroxy-3-methoxy-benzylideneamino)-ethane; hfacH = hexafluoroacetylacetone), which has an effective energy barrier of 21 K, a relaxation time of 2.7 × 10 −8 s, and an estimated blocking temperature of 1.2 K. 5 Since this breakthrough, combinations of Tb(III), Dy(III), Er(III), Sm(III), Yb(III), Gd(III), or Ho(III) with transition-metal ions such as Co(II), Mn(II/III), Fe(II/III), Ni(II), and Cu(II) have been extensively studied. 6 Other than the above examples of SMMs, the application of heterometallic 3d−4f clusters is limited. Nevertheless, their multiple adjacent metal sites together with their unique electronic and structural features offer the promise of catalytic performance.…”

“…However, their combination with 3d metal ions is essential to effectively suppress quantum tunneling and establish magnetic exchange between metal ions (3d–4f). − The first example of a 3d–4f SMM was [CuTb­(hfac) 2 (L)] 2 (H 3 L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxy-benzylideneamino)-ethane; hfacH = hexafluoroacetylacetone), which has an effective energy barrier of 21 K, a relaxation time of 2.7 × 10 –8 s, and an estimated blocking temperature of 1.2 K . Since this breakthrough, combinations of Tb­(III), Dy­(III), Er­(III), Sm­(III), Yb­(III), Gd­(III), or Ho­(III) with transition-metal ions such as Co­(II), Mn­(II/III), Fe­(II/III), Ni­(II), and Cu­(II) have been extensively studied …”

Magnetic Force Microscopy on Nanofibers—Limits and Possible Approaches for Randomly Oriented Nanofiber Mats

“…An antidot array of Dy 13 Fe 87 showed different morphological domains in MFM examinations [18]. Even molecular magnets have been investigated by MFM [19,20].…”

Magnetic Carbon Nanofiber Mats for Prospective Single Photon Avalanche Diode (SPAD) Sensing Applications

“…Magnetic nanofibers are produced by introducing magnetic nanoparticles into a polymer solution using an electrospinning process, which is simple and cost-effective [ 1 , 2 , 3 ]. Due to their high surface-to-volume ratio and high porosity, nanofibers have excellent sensitivity and high sensing performance, which makes them attractive for sensing applications such as detection of various gases, strain sensors, etc., [ 4 , 5 ].…”

“…In our previous study by Döpke et al, PAN/magnetite nanofiber mats were prepared and the magnetic properties were investigated [ 2 ]. Here, networks of magnetic nanofibers with beads that can be used to transport data in the form of domain walls moving along them and combined with objects that could be used to store data and transport [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 …”