Dear Sajjad,

Effectively there are exchange interaction calculations in the literature.

Please refer to the Elsevier Applied Science book, report as "Concerted European action on Magnets" by Mitchell, Coey, Givord, Harris, Hanitsch, ISBM 1 85166 383 5 (1989). This concerns with the early times of R2Fe14B developments.

You will find p 163 a paper by Gavigan, Givord, Li

p 174, paper by Franse, Sinnema, Verhoef, Radwanski, de Boer, Menovsky

p 188 paper by Pareti et al

p 203 paper by Buschow et al

and other papers

Please also see the Coehorn's works (from the Netherlands) not reported in this book but elsewhere who calculated for first principle approaches the interactions forces in those compounds.. so this was the early times, and you can find similar analysis from US and Japanese groups, at least in more recent investigations.

Burzo from Romania was also present in the field.

Good luck

Daniel

Respected D. Fruchart , Although your answer provided useful data and literature, however, I am still searching for numerical values of exchange interaction, if any, that may exist between, say two nano grains (CeFeB and NdFeB).

Journal of Physics D: Applied Physics

Intergranular exchange interaction in nanocrystalline hard magnetic rare earth–iron–boron-based melt-spun alloy ribbons

Z W Liu1,2 and H A Davies2

Published 29 June 2009 • 2009 IOP Publishing Ltd Journal of Physics D: Applied Physics, Volume 42, Number 14

Journal of the Physical Society of Japan

Quantum Theory of Rare-Earth Magnets

Takashi Miyake

and Hisazumi Akai

CD-FMat, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwano-ha, Chiba 277-8581, Japan

ESICMM, National Institute for Materials Science, Tsukuba 305-0047, Japan

Strong permanent magnets mainly consist of rare earths ....

arXiv:1801.03455v1 [cond-mat.mtrl-sci] 10 Jan 2018

Romanian Reports in Physics

, Vol. 63, Supplement, P. 1316–1328, 2011

Dedicated to Professor Marin Ivaşcu’s 80th Anniversary

MAGNETIC PROPERTIES AND EXCHANGE INTERACTIONS IN RARE-EARTH-IRON-

BASED COMPOUNDS

E. BURZO

“Babes-Bolyai” Univ, Faculty of Physics, Kogalniceanu Str 1, 400084, Cluj-Napoca, Romanian Academy, Cluj-Napoca Branch, Romania, July 11, 2011

I hope that these 3 more recent reports will be interesting for you.

Anyway there are many other literatures in terms of nano-grain exchange

Kind regards

Daniel