Long-range ferrimagnetic order in a two-dimensional supramolecular Kondo lattice

Abstract

Realization of long-range magnetic order in surface-supported two-dimensional systems has been challenging, mainly due to the competition between fundamental magnetic interactions as the short-range Kondo effect and spin-stabilizing magnetic exchange interactions. Spin-bearing molecules on conducting substrates represent a rich platform to investigate the interplay of these fundamental magnetic interactions. Here we demonstrate the direct observation of long-range ferrimagnetic order emerging in a two-dimensional supramolecular Kondo lattice. The lattice consists of paramagnetic hexadeca-fluorinated iron phthalocyanine (FeFPc) and manganese phthalocyanine (MnPc) molecules co-assembled into a checkerboard pattern on single-crystalline Au(111) substrates. Remarkably, the remanent magnetic moments are oriented in the out-of-plane direction with significant contribution from orbital moments. First-principles calculations reveal that the FeFPc-MnPc antiferromagnetic nearest-neighbour coupling is mediated by the Ruderman–Kittel–Kasuya–Yosida exchange interaction via the Au substrate electronic states. Our findings suggest the use of molecular frameworks to engineer novel low-dimensional magnetically ordered materials and their application in molecular quantum devices.

Enhanced magnetic spin–spin interactions observed between porphyrazine derivatives on Au(111)

“…These expected behaviors go along with the observed results. Similar spin-spin interaction effects on the Kondo resonance have been reported for several systems 20,37 . We want to stress that the coupling between the Kondo resonance and RKKY is emphasized in the current system due to the smaller molecule-molecule distance.…”

“…For the case of (1), the Kondo features tend to appear as a complex shape instead of a symmetric peak. These include FePc 15,16 , MnPc [17][18][19][20] , and hexadeca-fluorinated iron Pc 20 , where a dip or staircase-type Kondo resonance is reported. Examples of the (2) can be seen in the report for the molecules of NiPc and CuPc 21 .…”

An Isolated Molecule of Iron(II) Phthalocyanin Exhibits Quintet Ground‐State: A Nexus between Theory and Experiment

“…Metal phthalocyanines are extensively studied planar molecules possessing a great application potential as photosensitizers, electrocatalysts for CO 2 reduction, promising systems for spintronic devices, and energy harvesting from singlet fission . Among metal phthalocyanines, iron(II) phthalocyanine (FePc) holds a specific position mainly due to its superior applicability in various fields including single‐molecule quantum dots, electrocatalysts for oxygen reduction reaction, bifunctional catalysts for lithium‐oxygen batteries, model systems for heme‐like coordination chemistry and molecular frameworks to engineer novel low‐dimensional magnetically ordered materials . Despite of this paramount spectrum of applications being strongly related to the electronic and spin properties of FePc (Figure a), its spin characteristic is still a subject of intense scientific debate.…”

“…[6] Amongm etal phthalocyanines, iron(II) phthalocyanine (FePc)h olds as pecific position mainly due to itss uperior applicability in variousf ields including single-molecule quantum dots, [7] electrocatalysts for oxygen reduction reaction, [8][9][10] bifunctional catalysts for lithium-oxygen batteries, [11] model systems for heme-like coordinationc hemistry [12] and molecular frameworks to engineer novel low-dimensional magnetically ordered materials. [13] Despite of this paramount spectrum of applications being strongly related to the electronica nd spin properties of FePc (Figure 1a), its spin characteristic is still a subject of intense scientific debate. This is also due to the fact that large amount of studies on the FePc spin-state have been performed on thin-films and layered structures, [14,15] self-assembled systems [16] or moleculesi nteracting with surfaces.…”

Realistic indirect spin interactions between magnetic impurities on a metallic Pb(110) surface

“…In order to ensure the convergence of the RKKY interaction with respect to the cutoff E c , we evaluated the function J RKKY (r 1 , r 2 ) as in Eq. (25). Since the magnitude of the correction term J free RKKY (r 1 , r 2 ) varies inversely with the distance between the two impurities, impurities located at larger distances would require smaller values of E c in order to converge.…”